The Jargon File (version 4.4.7, 29 Dec 2003):

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 only
    supposed to be distributed to affiliates of source licensees. In spite of
    this, it soon spread by samizdat to a good many of the early Unix
    hackers.

    [1996 update: The Lions book lives again! It was put back in print as ISBN
    1-57398-013-7 from Peer-To-Peer Communications, with forewords by Dennis
    Ritchie and Ken Thompson. In a neat bit of reflexivity, the page before the
    contents quotes this entry.]

    [1998 update: John Lions's death was an occasion of general mourning in the
    hacker community.]


The Free On-line Dictionary of Computing (30 December 2018):

Lions Book

    "Source Code and Commentary on Unix level 6", by
   John Lions.

   The two parts of this book contained the entire source listing
   of the Unix Version 6 kernel, and 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
   licence 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.

   (http://peer-to-peer.com/catalog/history/lions.html).

   In 1996 it was reprinted as a "classic":

   [John Lions, "Lions' Comentary on UNIX 6th Edition with Source
   Code", Computer Classics Revisited Series, Peer-to-Peer
   Communications, 1996, ISBN 1-57398-013-7].

   [Jargon File]

   (1997-06-25)