Since The Book of Sires is an actual supplement for King Arthur Pendragon (5th edition, published by Chaosium/Nocturnal Media), this content is designed to promote a legitimate PDF version of that supplement.
While you are looking for a PDF, it is important to utilize official digital storefronts to ensure you receive the most up-to-date, high-quality version compatible with 5.2 or earlier editions: Chaosium Inc.: The official publisher offers the Book of Sires PDF directly on their website. DriveThruRPG:
A well-intentioned fan known as “Sir Beldon” once created a cleaned-up, re-typeset version based on the original print. This version circulates in small Pendragon Discord communities. While beautifully done, it remains and lacks key appendices.
Gain specific bonuses to Skills, Passions, or Attributes based on family achievements. Where to Find the PDF
if you want your players to have a deep connection to the history before Uther Pendragon.
None of these substitute for the full Book of Sires .