0
Your cart

Your cart is empty

Browse All Departments
Price
  • R100 - R250 (192)
  • R250 - R500 (972)
  • R500+ (4,161)
  • -
Status
Format
Author / Contributor
Publisher

Books > Science & Mathematics > Astronomy, space & time > General

Johannes Kepler - The Order of Things (Hardcover, 1st ed. 2020): Wolfgang Osterhage Johannes Kepler - The Order of Things (Hardcover, 1st ed. 2020)
Wolfgang Osterhage
R2,427 Discovery Miles 24 270 Ships in 18 - 22 working days

This book traces the development of Kepler's ideas along with his unsteady wanderings in a world dominated by religious turmoil. Johannes Kepler, like Galileo, was a supporter of the Copernican heliocentric world model. From an early stage, his principal objective was to discover "the world behind the world", i.e. to identify the underlying order and the secrets that make the world function as it does: the hidden world harmony. Kepler was driven both by his religious belief and Greek mysticism, which he found in ancient mathematics. His urge to find a construct encompassing the harmony of every possible aspect of the world - including astronomy, geometry and music - is seen as a manifestation of a deep human desire to bring order to the apparent chaos surrounding our existence. This desire continues to this day as we search for a theory that will finally unify and harmonise the forces of nature.

Morphology, Kinematics and Star Formation Across the Hubble Sequence of Galaxies (Hardcover, 1st ed. 2016): Santiago... Morphology, Kinematics and Star Formation Across the Hubble Sequence of Galaxies (Hardcover, 1st ed. 2016)
Santiago Erroz-Ferrer
R3,571 R3,311 Discovery Miles 33 110 Save R260 (7%) Ships in 10 - 15 working days

This thesis discusses the evolution of galaxies through the study of the morphology, kinematics, and star formation properties of a sample of nearby galaxies. The main body of the thesis describes the kinematic observations with the GHaFAS Fabry-Perot instrument on the William Herschel Telescope of a sample of 29 spiral galaxies. The work is closely related to the Spitzer Survey of Stellar Structure in Galaxies, and uses the mid-infrared data of that survey to determine key parameters of the galaxies studied. From these data, important results are obtained on streaming and other non-circular motions in galaxies, on the distribution and rates of star formation, and on how correlations of these parameters and of the rotation curve shape with basic galaxy parameters yield clues on the evolutionary processes taking place in disk galaxies.

Mapping the Spectrum - Techniques of Visual Representation in Research and Teaching (Hardcover): Klaus Hentschel Mapping the Spectrum - Techniques of Visual Representation in Research and Teaching (Hardcover)
Klaus Hentschel
R6,528 Discovery Miles 65 280 Ships in 10 - 15 working days

This book describes how advances in recording and printing technologies have influenced the research and teaching style of succeeding generations of physicists, chemists, and astronomers, particularly from the boom of spectrum analysis in the 1860s until the advent of quantum mechanics. Seemingly disparate strands such as spectrochemistry and cartography, instrument-design and science education are woven into the rich tapestry of one of the most fascinating and influential research-technologies of the late 19th and early 20th century.

Sun, Moon and Earth (Paperback): Robin Heath Sun, Moon and Earth (Paperback)
Robin Heath 1
R194 Discovery Miles 1 940 Ships in 10 - 15 working days

How many days are there between full moons - think you know? Is there an ancient key to the calendar hidden in stone circles? What is the magical secret of the Sun-Moon-Earth system? If you have ever wondered about eclipses, tides or the seasons, this amazing little book by acknowledged time-lord Robin Heath will quickly introduce you to the astonishing beauty of the primary cycles around this planet. Advanced wizarding at its best! "Timeless" RESURGENCE. "Fascinating" FINANCIAL TIMES. "Beautiful" LONDON REVIEW OF BOOKS. "Rich and Artful" THE LANCET. "Genuinely mind-expanding" FORTEAN TIMES. "Excellent" NEW SCIENTIST. "Stunning" NEW YORK TIMES. Small books, big ideas.

Boris Hessen: Physics and Philosophy in the Soviet Union, 1927-1931 - Neglected Debates on Emergence and Reduction (Hardcover,... Boris Hessen: Physics and Philosophy in the Soviet Union, 1927-1931 - Neglected Debates on Emergence and Reduction (Hardcover, 1st ed. 2021)
Chris Talbot; Translated by Chris Talbot; Edited by Olga Pattison; Translated by Olga Pattison
R2,653 Discovery Miles 26 530 Ships in 18 - 22 working days

This book presents key works of Boris Hessen, outstanding Soviet philosopher of science, available here in English for the first time. Quality translations are accompanied by an editors' introduction and annotations. Boris Hessen is known in history of science circles for his "Social and Economic Roots of Newton's Principia" presented in London (1931), which inspired new approaches in the West. As a philosopher and a physicist, he was tasked with developing a Marxist approach to science in the 1920s. He studied the history of physics to clarify issues such as reductionism and causality as they applied to new developments. With the philosophers called the "Dialecticians", his debates with the opposing "Mechanists" on the issue of emergence are still worth studying and largely ignored in the many recent works on this subject. Taken as a whole, the book is a goldmine of insights into both the foundations of physics and Soviet history.

The Chinese Astronomical Bureau, 1620-1850 - Lineages, Bureaucracy and Technical Expertise (Hardcover): Ping Ying Chang The Chinese Astronomical Bureau, 1620-1850 - Lineages, Bureaucracy and Technical Expertise (Hardcover)
Ping Ying Chang
R3,794 Discovery Miles 37 940 Ships in 10 - 15 working days

This book offers a new insight into one of the most interesting and long-lived institutions known to historians of science, the Chinese imperial Astronomical Bureau, which for two millennia observed, recorded, interpreted and predicted the movements of the celestial bodies. Utilising archival material, such as the resumes written for imperial audiences and personnel administration records, the book traces the rise and fall of more than thirty hereditary families serving at the Astronomical Bureau from the late Ming period to the end of the Qing dynasty. The book also presents an in-depth view into the organisation and function of the Bureau and succinctly charts the impacts of historical developments during the Ming and Qing periods, including the Regency of Prince Dorgon, the influence of the Jesuits, the relationship between the Kangxi and Yongzheng emperors and the He family and the failure of the bureau to predict correctly the solar eclipse of 1730. Presenting a social history of the Qing Astronomical Bureau from the perspective of hereditary astronomer families, this book will be of interest to scholars and students of Chinese Imperial history, the history of science and Asian history.

Master of Galactic Astronomy: A Biography of Jan Hendrik Oort (Hardcover, 1st ed. 2021): Pieter C. van der Kruit Master of Galactic Astronomy: A Biography of Jan Hendrik Oort (Hardcover, 1st ed. 2021)
Pieter C. van der Kruit
R1,038 R891 Discovery Miles 8 910 Save R147 (14%) Ships in 18 - 22 working days

This accessible and entertaining biography chronicles the life and triumphs of astronomer Jan Hendrik Oort, who helped lay the foundations of modern astronomy in the 20th century. The book puts into context some of Oort's most significant achievements, including his discovery that the Milky Way rotates, as well as his famous hypothesis that our Solar System is surrounded by a reservoir of comets - now simply known as the Oort Cloud. Written by Oort's former student, this fascinating story also delves into Oort's pivotal role in the foundation of major astronomical facilities, including radio telescopes in the Netherlands and the European Southern Observatory (ESO), which now operates the most successful astronomical observatories in the world. The book draws extensively on new archival research through the Oort Archives, along with personal reminiscences by Oort's son and astronomer-grandson, to paint a more detailed picture of Oort's life not just as an astronomer, but also as a husband, father, and citizen. The strong public interest in comets triggered by the Rosetta mission to comet 67P/Churyumov-Gerasimenko and the recently discovered interstellar comet in the Solar System make this book particularly timely.

An Introduction to Nuclear Astrophysics - The Formation and the Evolution of Matter in the Universe (Hardcover, 1980 ed.): J.... An Introduction to Nuclear Astrophysics - The Formation and the Evolution of Matter in the Universe (Hardcover, 1980 ed.)
J. Audouze, S. Vauclair
R2,752 Discovery Miles 27 520 Ships in 18 - 22 working days

TO NUCLEAR ASTROPHYSICS The Formation and the Evolution of Matter in the Universe JEAN AUDOUZE lnstitut d'Astrophysique de Paris, France and SYLVIE VA UCLAI R DAPHE, Ohservatoire de Meudon, France and lnstitut d'Astrophysique, Paris D, REIDEL PUBLISHING COMPANY DORDRECHT: HOLLAND/BOSTON: U. S. A. LONDON: ENGLAND Library of Congre~ Cataloging in Publication Data Audouzc. Jean An introduction to nuclear astrophysics. (Geophysics and astrophysics monographs; v. 18) En!. and updated translation of L'Astrophysique nuclt\aire. Includes bibliographies and index. \. Nuclear astrophysics. I. Vauclair, Sylvie, joint author. II. Title. III. Series. QB464. A9313 1979 523. 01'9'7 79-20752 ISBN-13: 978-90-277-1053-6 e-ISBN-13: 978-94-009-9477-5 DO I: 10. 1007/978-94-009-9477-5 Published by D. Reidel Publishing Company, P. O. Box 17. Dordrecht, Holland Sold and distributed in the U. S. A. , Canada, and Mexico by D. Reidel Publishing Company, Inc. Lincoln Building. 160 Old Derby Street, Hingham, Mass. 02043, U. S. A. All Rights Reserved Copyright (c) 1980 by D. Reidel Publishing Company, Dordrecht, Holland Softcover reprint of the hardcover 1st edition 1980 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any informational storage and retrieval system, without written permission from the copyright owner TABLE OF CONTENTS IX FOREWORD INTRODUCTION xi XXI ACKNOWLEDGEMENTS CHAPTER I / THE OBSERVATIONAL BASIS OF NUCLEAR ASTROPHYSICS 1. 1. The Importance of the Four Fundamental Interactions 1 1. 2.

Hamiltonian Mechanics - Integrability and Chaotic Behavior (Hardcover, 1994 ed.): John Seimenis Hamiltonian Mechanics - Integrability and Chaotic Behavior (Hardcover, 1994 ed.)
John Seimenis
R4,349 Discovery Miles 43 490 Ships in 18 - 22 working days

This volume contains invited papers and contributions delivered at the International Conference on Hamiltonian Mechanics: Integrability and Chaotic Behaviour, held in Tornn, Poland during the summer of 1993. The conference was supported by the NATO Scientific and Environmental Affairs Division as an Advanced Research Workshop. In fact, it was the first scientific conference in all Eastern Europe supported by NATO. The meeting was expected to establish contacts between East and West experts as well as to study the current state of the art in the area of Hamiltonian Mechanics and its applications. I am sure that the informal atmosphere of the city of Torun, the birthplace of Nicolaus Copernicus, stimulated many valuable scientific exchanges. The first idea for this cnference was carried out by Prof Andrzej J. Maciejewski and myself, more than two years ago, during his visit in Greece. It was planned for about forty well-known scientists from East and West. At that time participation of a scientist from Eastern Europe in an Organising Committee of a NATO Conference was not allowed. But always there is the first time. Our plans for such a "small" conference, as a first attempt in the new European situation -the Europe without borders -quickly passed away. The names of our invited speakers, authorities in their field, were a magnet for many colleagues from all over the world.

Atomic Emission Spectra of Neutral Noble Gases in the Infrared Spectral Range (Hardcover, 1st ed. 2020): Svatopluk Civis,... Atomic Emission Spectra of Neutral Noble Gases in the Infrared Spectral Range (Hardcover, 1st ed. 2020)
Svatopluk Civis, Ekaterina Zanozina, Adam Pastorek, Petr Kubelik, Martin Ferus, …
R2,653 Discovery Miles 26 530 Ships in 18 - 22 working days

This book is an invaluable guide to calibrating any infrared spectrum using noble gases as a reference. Featuring a detailed graphical and tabular overview of highly excited (Rydberg) states of neutral noble gases in the infrared range of 700-7000 cm-1, it helps researchers by providing high-precision experimental data that can be used in almost every infrared spectroscopic laboratory.

On the Total Solar Eclipse of July 18th, 1860, Observed at Rivabellosa, Near Miranda De Ebro in Spain (Hardcover): Warren... On the Total Solar Eclipse of July 18th, 1860, Observed at Rivabellosa, Near Miranda De Ebro in Spain (Hardcover)
Warren 1815-1889 de la Rue
R766 Discovery Miles 7 660 Ships in 18 - 22 working days
General Theory of Light Propagation and Imaging Through the Atmosphere (Hardcover, 2nd ed. 2022): T. Stewart McKechnie General Theory of Light Propagation and Imaging Through the Atmosphere (Hardcover, 2nd ed. 2022)
T. Stewart McKechnie
R2,794 Discovery Miles 27 940 Ships in 18 - 22 working days

This 2nd edition lays out an updated version of the general theory of light propagation and imaging through Earth's turbulent atmosphere initially developed in the late '70s and '80s, with additional applications in the areas of laser communications and high-energy laser beam propagation. New material includes a chapter providing a comprehensive mathematical tool set for precisely characterizing image formation with the anticipated Extremely Large Telescopes (ELTS), enabling a staggering range of star image shapes and sizes; existing chapters rewritten or modified so as to supplement the mathematics with clearer physical insight through written and graphical means; a history of the development of present-day understanding of light propagation and imaging through the atmosphere as represented by the general theory described. Beginning with the rudimentary, geometrical-optics based understanding of a century ago, it describes advances made in the 1960s, including the development of the 'Kolmogorov theory,' the deficiencies of which undermined its credibility, but not before it had done enormous damage, such as construction of a generation of underperforming 'light bucket' telescopes. The general theory requires no a priori turbulence assumptions. Instead, it provides means for calculating the turbulence properties directly from readily-measurable properties of star images.

Astrotopia - The Dangerous Religion of the Corporate Space Race (Hardcover): Mary-Jane Rubenstein Astrotopia - The Dangerous Religion of the Corporate Space Race (Hardcover)
Mary-Jane Rubenstein
R641 Discovery Miles 6 410 Ships in 9 - 17 working days

A revealing look at the parallel mythologies behind the colonization of Earth and space-and a bold vision for a more equitable, responsible future both on and beyond our planet. As environmental, political, and public health crises multiply on Earth, we are also at the dawn of a new space race in which governments team up with celebrity billionaires to exploit the cosmos for human gain. The best-known of these pioneers are selling different visions of the future: while Elon Musk and SpaceX seek to establish a human presence on Mars, Jeff Bezos and Blue Origin work toward moving millions of earthlings into rotating near-Earth habitats. Despite these distinctions, these two billionaires share a core utopian project: the salvation of humanity through the exploitation of space. In Astrotopia, philosopher of science and religion Mary-Jane Rubenstein pulls back the curtain on the not-so-new myths these space barons are peddling, like growth without limit, energy without guilt, and salvation in a brand-new world. As Rubenstein reveals, we have already seen the destructive effects of this frontier zealotry in the centuries-long history of European colonialism. Much like the imperial project on Earth, this renewed effort to conquer space is presented as a religious calling: in the face of a coming apocalypse, some very wealthy messiahs are offering an other-worldly escape to a chosen few. But Rubenstein does more than expose the values of capitalist technoscience as the product of bad mythologies. She offers a vision of exploring space without reproducing the atrocities of earthly colonialism, encouraging us to find and even make stories that put cosmic caretaking over profiteering.

The Mass of Galaxies at Low and High Redshift - Proceedings of the European Southern Observatory and Universitats-Sternwarte... The Mass of Galaxies at Low and High Redshift - Proceedings of the European Southern Observatory and Universitats-Sternwarte Munchen Workshop Held in Venice, Italy, 24-26 October 2001 (Hardcover, 2003 ed.)
Ralf Bender, Alvio Renzini
R1,301 Discovery Miles 13 010 Ships in 10 - 15 working days

Measuring the masses of galaxies as a function of redshift is perhaps one of the most challenging open issues in current astronomical research. The evolution of the baryonic and dark matter components of galaxies is not only a critical test of the hierarchical formation paradigm, but ultimately also provides new clues on the complex interplay between star formation, the cooling and heating of gas and galaxy merging processes.This book reviews current techniques to measure the baryonic (stellar) and dark masses of nearby galaxies, and focusses on ongoing attempts to measure these same quantities in galaxies at higher and higher redshifts. It also gives room to future perspectives, with special emphasis on new survey projects and satellite missions.

Intersections of Religion and Astronomy (Paperback): Aaron Ricker, Chris Corbally, Darry Dinell Intersections of Religion and Astronomy (Paperback)
Aaron Ricker, Chris Corbally, Darry Dinell
R1,327 Discovery Miles 13 270 Ships in 10 - 15 working days

This volume examines the way in which cultural ideas about "the heavens" shape religious ideas and are shaped by them in return. Our approaches to cosmology have a profound effect on the way in which we each deal with religious questions and participate in the imaginative work of public and private world-building. Employing an interdisciplinary team of international scholars, each chapter shows how religion and cosmology interrelate and matter for real people. Historical and contemporary case studies are included to demonstrate the lived reality of a variety of faith traditions and their interactions with the cosmos. This breadth of scope allows readers to get a unique overview of how religion, science and our view of space have, and will continue to, impact our worldviews. Offering a comprehensive exploration of humanity and its relationship with cosmology, this book will be an important reference for scholars of Religion and Science, Religion and Culture, Interreligious Dialogue and Theology, as well as those interested in Science and Culture and Public Education.

History of the Plurality of Worlds - The Myths of Extraterrestrials Through the Ages (Hardcover, 1st ed. 2020): Pierre Connes History of the Plurality of Worlds - The Myths of Extraterrestrials Through the Ages (Hardcover, 1st ed. 2020)
Pierre Connes; Edited by James Lequeux
R4,299 Discovery Miles 42 990 Ships in 18 - 22 working days

Modern research has demonstrated that many stars are surrounded by planets-some of which might contain the right conditions to harbor life. This has only reinforced a question that has been tormenting scientists, philosophers and priests since Antiquity: Are there other inhabited worlds beyond our own? This book analyzes the many ways that humans have argued for and depicted extraterrestrial life over the centuries. The first known texts about the subject date from as early as the 6th century BC. Since that time, countless well-known historical characters like Lucretius, Aristotle, Thomas Aquinas, Cusanus, Bruno, Kepler, Descartes, and Huygens contributed to the debate; here, their lesser known opinions on the subject are studied in detail. It is often difficult for the modern mind to follow the thinking of our ancestors, which can only be understood when placed in the relevant context. The book thus extends its scope to the evolution of ideas about cosmology in general, as well as the culture in which these great thinkers wrote. The research is presented with the author's insights and humor, making this an easy and enjoyable read.

Chaotic Worlds: from Order to Disorder in Gravitational N-Body Dynamical Systems (Hardcover, 2006 ed.): B. A. Steves, A.J.... Chaotic Worlds: from Order to Disorder in Gravitational N-Body Dynamical Systems (Hardcover, 2006 ed.)
B. A. Steves, A.J. Maciejewski, M. Hendry
R4,201 Discovery Miles 42 010 Ships in 18 - 22 working days

Based on the recent NATO Advanced Study Institute "Chaotic Worlds: From Order to Disorder in Gravitational N-Body Dynamical Systems", this state of the art textbook, written by internationally renowned experts, provides an invaluable reference volume for all students and researchers in gravitational n-body systems. The contributions are especially designed to give a systematic development from the fundamental mathematics which underpin modern studies of ordered and chaotic behaviour in n-body dynamics to their application to real motion in planetary systems. This volume presents an up-to-date synoptic view of the subject.

Observations Made at the Magnetical and Meteorolgical Observatory at Toronto in Canada [microform] (Hardcover): Edward Sabine Observations Made at the Magnetical and Meteorolgical Observatory at Toronto in Canada [microform] (Hardcover)
Edward Sabine
R1,063 Discovery Miles 10 630 Ships in 18 - 22 working days
Acta Academiae Scientiarum Imperialis Petropolitanae, Vol. 2: Pro Anno 1779 (Classic Reprint) (Latin, Hardcover):... Acta Academiae Scientiarum Imperialis Petropolitanae, Vol. 2: Pro Anno 1779 (Classic Reprint) (Latin, Hardcover)
Imperatorskai?a? Akadem?i?a Nauk
R827 Discovery Miles 8 270 Ships in 10 - 15 working days
International Catalogue Of Scientific Literature, 1910: L, General Biology (Classic Reprint) (German, Paperback): Royal Society... International Catalogue Of Scientific Literature, 1910: L, General Biology (Classic Reprint) (German, Paperback)
Royal Society of London
R535 Discovery Miles 5 350 Ships in 10 - 15 working days
International Catalogue Of Scientific Literature, Vol. 14: Q, Physiology (Classic Reprint) (German, Paperback): Royal Society... International Catalogue Of Scientific Literature, Vol. 14: Q, Physiology (Classic Reprint) (German, Paperback)
Royal Society of London
R938 Discovery Miles 9 380 Ships in 10 - 15 working days
International Catalogue Of Scientific Literature, 1906, Vol. 4: C, Physics (Classic Reprint) (German, Paperback): Royal Society... International Catalogue Of Scientific Literature, 1906, Vol. 4: C, Physics (Classic Reprint) (German, Paperback)
Royal Society of London
R964 Discovery Miles 9 640 Ships in 10 - 15 working days
Sensitivity Analysis in Earth Observation Modelling (Paperback): George P. Petropoulos, Prashant K Srivastava Sensitivity Analysis in Earth Observation Modelling (Paperback)
George P. Petropoulos, Prashant K Srivastava
R2,418 R2,287 Discovery Miles 22 870 Save R131 (5%) Ships in 10 - 15 working days

Sensitivity Analysis in Earth Observation Modeling highlights the state-of-the-art in ongoing research investigations and new applications of sensitivity analysis in earth observation modeling. In this framework, original works concerned with the development or exploitation of diverse methods applied to different types of earth observation data or earth observation-based modeling approaches are included. An overview of sensitivity analysis methods and principles is provided first, followed by examples of applications and case studies of different sensitivity/uncertainty analysis implementation methods, covering the full spectrum of sensitivity analysis techniques, including operational products. Finally, the book outlines challenges and future prospects for implementation in earth observation modeling. Information provided in this book is of practical value to readers looking to understand the principles of sensitivity analysis in earth observation modeling, the level of scientific maturity in the field, and where the main limitations or challenges are in terms of improving our ability to implement such approaches in a wide range of applications. Readers will also be informed on the implementation of sensitivity/uncertainty analysis on operational products available at present, on global and continental scales. All of this information is vital in the selection process of the most appropriate sensitivity analysis method to implement.

Accreting Binaries - Nature, formation, and evolution (Hardcover): Sylvain Chaty Accreting Binaries - Nature, formation, and evolution (Hardcover)
Sylvain Chaty
R3,272 Discovery Miles 32 720 Ships in 10 - 15 working days
Learning Astronomy by Doing Astronomy (Paperback, Second Edition): Stacy Palen, Ana Larson Learning Astronomy by Doing Astronomy (Paperback, Second Edition)
Stacy Palen, Ana Larson
R1,154 Discovery Miles 11 540 Ships in 10 - 15 working days

Research shows that students learn best by doing. This workbook, written by two master teachers, contains 36 field-tested activities, including nine new to the Second Edition, that span the introductory astronomy course and can be used in any size of classroom. Each activity is now self-contained with an introduction that provides necessary background material for students. Activities are built around a concept that leads students from basic knowledge to a deeper understanding through guided interactions. The Second Edition is supported by Smartwork5, so instructors can easily assess student understanding.

Free Delivery
Pinterest Twitter Facebook Google+
You may like...
A Focus on Ratios and Proportions…
Marjorie M. Petit, Robert E. Laird, … Paperback R1,149 Discovery Miles 11 490
Mental Computation and Estimation…
Charalampos Lemonidis Paperback R1,665 Discovery Miles 16 650
Statistics for K-8 Educators
Robert Rosenfeld Hardcover R4,355 Discovery Miles 43 550
Women and Freedom in Early America
Larry Eldridge Hardcover R2,892 Discovery Miles 28 920
A Practical Guide to Teaching…
Clare Lee, Robert Ward-Penny Paperback R1,040 Discovery Miles 10 400
Courtly Feasts to Kremlin Banquets - A…
Oksana Y Zakharova, Sergey N Pushkaryov Hardcover R869 Discovery Miles 8 690
Creativity and Learning in Secondary…
Andrew McCallum Hardcover R4,208 Discovery Miles 42 080
An Introduction to the History of the…
George Chalmers Paperback R573 Discovery Miles 5 730
The Malaspina Expedition 1789-1794…
Andrew David, Felipe Fernandez-Armesto, … Paperback R1,353 Discovery Miles 13 530
A Political and Civil History of the…
Timothy Pitkin Paperback R678 Discovery Miles 6 780

 

Partners