Original source can be obtained from:
http://www.bzip.org/

The file README.DELETED contains a list of deleted files.

cvs hint:
cvs import src/contrib/bzip2-1.0 BZIP v1_0_?

This is used by:
lib/libbz2/
lib/libstand/
usr.bin/bzip2/
usr.bin/bzip2recover/