This Encyclopedia is the first to compile some 500,000 pseudonyms of roughly 270,000 people. Besides pseudonyms in the narrower sense, initials, nick names, oder names, birth and married names etc. are included. The volumes 1 to 9 list persons by their real names in alphabetical order, in volumes 10 to 16, the pseudonyms are listed alphabetically and the real names provided. To make identification easier, year and place of birth and death are provided where available, as are profession, nationality and more personal data.

The Genealogy and Family History Collection is a unique set of materials that describes the histories and narratives of particular American families. The Collection brings to life pre-1923 books that contain information such as birth, death, marriage, property and migration records of specific families. Many of these families followed interesting migration and movement patterns from Western Europe and beyond to the United States well over 200 years ago. Included in these volumes is information such as last wills and testaments, period photographs of towns, buildings and landscapes, portraits of family members, and descriptions of business interactions. Encompassing such comprehensive and personal information, this collection will appeal to genealogists, family history researchers, as well as descendants and casual historians.