Lions Book: n. "Source Code and Commentary on UNIX level 6

:Lions Book: n. "Source Code and Commentary on UNIX level 6",
by John Lions. The two parts of this book contained (1) the entire
source listing of the UNIX Version 6 kernel, and (2) a commentary
on the source discussing the algorithms. These were circulated
internally at the University of New South Wales beginning 1976--77,
and were, for years after, the *only* detailed kernel
documentation available to anyone outside Bell Labs. Because
Western Electric wished to maintain trade secret status on the
kernel, the Lions book was never formally published and was only
supposed to be distributed to affiliates of source licensees (it is
still possible to get a Bell Labs reprint of the book by sending a
copy of a V6 source license to the right person at Bellcore, but
*real* insiders have the UNSW edition). In spite of this, it
soon spread by samizdat to a good many of the early UNIX
hackers.
-- The AI Hackers Dictionary