Encyclopædia Britannica Eleventh Edition

The 29-volume Encyclopædia Britannica Eleventh Edition was the 1910-1911 version of the encyclopædia. Authors included Edmund Gosse, J. B. Bury, Algernon Charles Swinburne, John Muir, Peter Kropotkin, T. H. Huxley, William Michael Rossetti, Ernest Rutherford, and Bertrand Russell.

It is in the public domain, but there are some online versions that claim copyright.