Cassidy, M.J., Quantum field theory and acausal spacetimes, Jan. 1998. PhD thesis.

Stephen Hawking's office contained more than 300 books, all located on the bookshelves above the kitchen counter. They date as early as his student years, and the bulk corresponds to his long professional career from the 1960s to the 2010s. From the 1990s onwards Stephen would have used digital versions increasingly, so the books in his bookcases were a select subset. While some items are rare copies -like the dissertations he advised or book drafts- most of the library contents are rather standard prints. The majority contain significant individual marks, and even for those that do not, the connection to Hawking is evident. Books by friends and colleagues often contain inscriptions and inserts that evidence their relationship. Others remind of places he visited, conferences he attended, or relate to having become a celebrity and inspiration throughout the world. Of the books that he authored, there are usually multiple versions, translations, and occasionally draft versions. A good portion of the books also contain inserts such as notes by the authors or editors, receipts, and occasionally unrelated material that found its way into them around the time of their acquisition. A portion of them has also been bookmarked with post-its by Stephen's assistants pointing to the sections most relevant to show visitors.