Our ancient sources include:
The Book of Matthew 19:12
Suetonius: Life of Nero (C.J. Rolfe translation)
Strabo: Geography (Horace Leonard Jones translation)
Eusebius’ Church History (Arthur Cushman McGiffert translation)
Claudian: Against Eutropius. (Maurice Platnauer translation)
Our modern sources include:
Shaun Tougher: The Roman Castrati: Eunuchs in the Roman Empire.
John T. Quinn: “Earinus the Eunuch: Martial (from Book 9) and Statius (Silvae 3.4)”
Unroman Romans: Religious Castration
Donald Lateiner: A Review of Eunuchs in Antiquity and Beyond by Shaun Tougher.
Daniel F. Caner: “The Practice and Prohibition of Self-Castration in Early Christianity.”
Theoi: The Cult of Artemis
Jean D. Wilson, Claus Rhoehrborn. “Long-Term Consequences of Castration in Men: Lessons from the Skoptzy and the Eunuchs of the Chinese and Ottoman Courts.”
Jennifer A. Blackwell: “Spadones et Castrati: Two Types of Eunuchs in Roman Literature and Law.”
Robert D. Martin, M.D. “Unmanned: An Unnatural History of Human Castration.”
Roger Pierce: “Cybele’s castration clamps – medical apparatus of the Magna Mater.”
Alfred G. Francis. “On a Romano-British Castration Clamp used in the Rites of Cybele.”
Cheryl Morgan: “Earinus: Roman Civil Rights Activist?”
Georges Sideris: “The Rise and Fall of the High Chamberlain Eutropius: Eunuch Identity, the Third Sex and Power in Fourth-Century Byzantium.”
J.B. Bury: History of the Later Roman Empire.
Rhiannon M. Rowlands: “Eunuchs and Sex: Beyond Sexual Dichotomy in the Roman World.”