Stephen Hawking ownership signature within ''Astrophysical Quantities'', one of the most referenced books in the discipline of astrophysics. London: The Athlone Press, 1964 second edition by Clabon Allen. Signed by Hawking on the front free endpaper in black ballpoint, ''S.W. Hawking'', with the bookseller's date in pencil reading ''4-6-70'', revealing when Hawking most likely purchased and signed the book. At this time in 1970, Hawking was doing his most vigorous work on black holes, and theorized what is now accepted as the second law of black hole dynamics. This book, ''Astrophysical Quantities'' was probably used repeatedly by the legendary scientist at the time. Book measures 6.875'' x 9.75'', bound in publisher's forest green boards and housed in original dust jacket. Jacket has some sunning to spine and a few nicks, in very good condition. Book itself is near fine. With University Archives COA.