A detailed family tree.

Historical summary and timeline.

The full source archives of the University of California at Berkeley's Computer Systems Research Group, for sale on a 4-CD set.

Various drawings, pictures, and information on the red devil BSD mascot.

Lengthy encyclopedia-quality article from Bell Labs, covering the early days to the present versions.

1979 conference paper by Dennis Ritchie. "Concentrates on the evolution of the file system, the process-control mechanism, and the idea of pipelined commands. Some attention is paid to social conditions during the development of the system."

Built to foster the "the preservation and maintenance of historical and non-mainstream UNIX systems." Mailing list and archives. Includes early Unix source code, from 1973 through the 1990s.

Ritchie and Thompson's famous Communications of the ACM paper from 1974. An authoritative and technical overview of the operating system.

Historical comparison of Unix and the free software movement.

History paper detailing the people and places involved in developing Unix.