Recommended Books on Clerical Celibacy

The Apostolic Origins of Priestly Celibacy, Christian Cochini, S.J.
Clerical Celibacy in East and West, Roman Cholij
The Case of Clerical Celibacy:Its Historical Development & Theological Foundations, Alfons Maria Cardinal Stickler
Theology of Priestly Celibacy, Stanley L.Jaki
Celibacy in the Early Church, Stefan Heid