Sefer Zadok is the name of a Sadducean text, containing the doctrines of the Sadducees, allegedly written by their founder, Zadok. No copies of this text are extant today, except for quotes in the polemics of Rabbinic and Karaite Jewish scholars of that time period.
The Sefer Zadok is also referred to in texts by Josephus and in the Talmud as a text containing the doctrines and beliefs of Sadduccee Judaism. There are many stories, anecdotes, and religious and political ideas attributed to the Sadduccees in these texts. These works were, however, produced by those who stood in opposition to the Sadduccees (primarily the Pharisees) and are thus suspect. Little else is known about this text and those who followed its teachings.
References
Sefer Zadok Wikipedia(Text) CC BY-SA