‘The Four Laws of Black Hole Mechanics’. Offprint from: Communications in Mathematical Physics. Vol. 31, pp.161-170. [Berlin:] Springer-Verlag, 1973.

Part of Stephen Hawking's Office collection, but not coming directly from the office, are a collection of offprints of varied publications authored by him over the years. Offprints are distributed by publishers to authors as complimentary copies of their work, most often as stand-alone booklets of larger collectively authored publications such as journal issues or encyclopedias. Until the 1990s, these were one of the main ways for authors to quickly distribute their first issue to close acquaintances. With the advent of photocopying and digital publishing, their value has become largely symbollic, as the proof of finished work.