Time Lord guide (How to be a Time Lord)

The Doctor possessed a "stuffy old guide" to Time Lords. Towards the end of his life, the Eleventh Doctor partially repurposed his copy of the book into a guide on how to be the Doctor for his next incarnation, filling it with additional pages, including replacing some entirely, and jotting down additional notes. (PROSE: How to be a Time Lord)

The Thirteenth Doctor later incorporated excerpts from this altered book into another book that she wrote for her next incarnation, to which she added further notes and updates. (PROSE: A Short History of Everyone)

Topics covered within the guide included, but were not limited to, the history of Gallifrey, Time Lord biology (compared with human biology), regeneration, the Time Lord Academy, and much more. The Eleventh Doctor's additions included a rundown of his life, adventures, and companions up to that point, which were later expanded upon by the Thirteenth Doctor. (PROSE: How to be a Time Lord, A Short History of Everyone)