Sources
Browse the public-domain works behind the encyclopedia database, including volumes, source quality, scans, and copyright notes.
1910–1911
Encyclopaedia Britannica · 11th edition
First published before 1931; treated as public domain in the United States. Verify jurisdiction before redistribution outside the U.S.
1920
The Encyclopedia Americana · 1920 edition
Published in 1920; public domain in the United States.
1902–1905
The New International Encyclopaedia · First edition
Published before 1931; public domain in the United States. OCR quality varies by volume.
1873–1879
The American Cyclopaedia · Revised edition
Published before 1931; public domain in the United States.
1922
The New Gresham Encyclopedia · Complete edition
Early 1920s publication; Project Gutenberg provides public-domain text for U.S. use. Verify jurisdiction outside the U.S.