History of Unix and causes for its popularity. "This document is designed to give people with no previous UNIX experience some sense of what UNIX is. This document will cover the history of UNIX and an introduction to UNIX."

University of Indiana Knowledge Base article. Summary of Unix versions and links to related entries.

A detailed overview of Unix people and components, 1975-1984.

History and overview from the FreeBSD Handbook.

Several classic Unix papers dating back to 1973. Most reports are Gzipped PostScript, some are in PDF.

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

Several historic technical reports, anecdotes, and stories from one of the fathers of Unix.

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

Historical comparison of Unix and the free software movement.

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

Steve Hosgood's work with an early 1980s Unix clone. Includes some utility sources.

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."

Chapter-length article by Ronda Hauben on "how the need to automate telephone support operations in the U.S. in the late 1960s and the early 1970s nourished the birth and development of the UNIX operating system and how academic computer science contributed to and gained from the development of UNIX."

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.

Historical summary and timeline.

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

A detailed family tree.

Lists of release dates and dependencies for the various Unix flavors. A graphical representation of the Unix family tree is planned.

Archives at Bell Labs of the 1979 manual. Troff source and formatted Gzipped PostScript/PDF versions.