- Encyclopædia Britannica, Ninth Edition (1875–1889)
- 1911 Encyclopædia Britannica (11th edition)
- 1922 Encyclopædia Britannica (12th edition)
The first 12 editions of the Encyclopædia Britannica are all in the public domain.
The 13th edition (1926) is the same as the 11th, except that the three supplementary volumes of the 12th edition have been replaced. The usual sources for information on copyright renewals show no record of the copyright having been renewed.
The original 14th edition (1929–1933) was a completely new edition in 24 volumes. No record of copyright renewal has been found.
In 1933 a revision process was begun on the 14th edition, resulting in publication in various states of revision until 1973. No record could be found of copyright renewal of any revisions issued before 1946. For anything published in 1946 only a few parts had their copyright renewed. After 1946 all versions should be treated as protected.
The 15th edition began in 1974, and is fully protected by copyrights.
Notes on various editions
- 12th – This edition includes extensive articles on the battles of World War I. When the 13th edition was published the length of these articles was significantly reduced.
- 14th – The 14th was produced over a period of 45 years. The editorial changes over the years were so vast that the content of an early 14th and a late 14th hardly resemble each other. Many articles included in the first version were omitted in later ones.
- WikiProject 1911 Encyclopædia Britannica - working group to bring 1911 Encyclopædia Britannica into Wikisource