Databases and public access catalogs are being used extensively by the public and the academic and business communities as major sources of information. Most users want to access these databases directly to locate the information they need. Increasingly, users are demanding user-friendly databases that will assist them in finding conceptual information effectively. The lack of compatibility or standardization among many different indexing vocabularies and thesauri makes it difficult to find related information in information retrieval systems containing many different online databases. This book provides a thought-provoking new perspective on the role of vocabulary control in providing access to the conceptual information found in online databases and catalogs. The first three chapters provide a basis for understanding the structure of vocabulary control systems used for the indexing of conceptual information. Chapters 4 and 5, which deal with thesaural relationship model formulation and investigation, will be of the greatest interest to designers of online databases and public access catalogs who are striving to improve access to conceptual information from multiple databases. Researchers and developers of thesauri, who are faced with the problems of compatibility and convertibility, will also be interested in testing the applicability of the thesaural relationship model for other vocabulary control systems. The findings reported in chapter six will be of particular interest to database producers and vendors. Although switching and frequency online search strategies for database search engines are not yet available, end-users and experienced searchers can still incorporate these concepts to improve the effectiveness of their searches. Recommendations resulting from this investigation are summarized in the final chapters. With the proliferation of online databases and the increasing number of inexperienced users, the development of new search strategies to facilitate easier searches is critical. This book will be required reading for everyone involved in this effort.