- Unix V8 /usr/src/libc/gen/{regcomp.c,regerror.c,regex.c,regexec.c,regprog.c,regsub.c}, /usr/include/regexp.h
- Unix V9 libc/gen/{regcomp.c,regerror.c,regexec.c,regsub.c}, include/regexp.h, include/CC/Regexp.h, and cmd/cfront/CC/Regexp.h
- Unix V10 libc/gen/{regcomp.c,regerror.c,regexec.c,regprog.c,regsub.c}