"BSD - Berkeley System Distribution, first released in 1977 by Bill Joy. At Berkeley University and other campuses students and post-graduates worked on improvements of the AT&T operating system Unix. Most significant contributions were the inclusion of the Internet Protocols (IP) in Unix and the BSD licence. Besides Linux, BSD is another stream of how a version of Unix became 'free'. Since the closure of the research group at Berkeley, University of California, BSD lives on through the three follow-up projects NetBSD, FreeBSD and OpenBSD."
- Comparing BSD and GPL Licenses
- Essay: Twenty Years of Berkeley Unix: From AT&T-Owned to Freely Redistributable. Marshall Kirk McKusick