|←Author Index: Pa||Theodore Parker
- “Parker, Theodore” by John Weiss in The American Cyclopædia, 1879
- “Parker, Theodore” in Encyclopædia Britannica (9th ed.), 1885.
- Octavius Brooks Frothingham, “Parker, Theodore,” Appletons' Cyclopædia of American Biography. New York: D. Appleton and Co., 1900.
- John White Chadwick, “Parker, Theodore,” The New International Encyclopædia. New York: Dodd, Mead and Co., 1905.
- “Parker, Theodore” in The Nuttall Encyclopædia by James Wood, London: Frederick Warne and Co., Ltd., 1907.
- “Parker, Theodore,” in A Short Biographical Dictionary of English Literature by John William Cousin, London: J. M. Dent & Sons, 1910.
- “Parker, Theodore” in Encyclopædia Britannica, (11th ed.), 1911
- “Parker, Theodore” in The Encyclopedia Americana. New York, 1920.
- “Parker, Theodore,” Collier's New Encyclopedia. New York: P.F. Collier & Son Co., 1921.
Works by this author published before January 1, 1923 are in the public domain worldwide because the author died at least 100 years ago. Translations or editions published later may be copyrighted. Posthumous works may be copyrighted based on how long they have been published in certain countries and areas.