TOMS449 is a FORTRAN77 library which implements ACM TOMS algorithm 449, which solves linear programming problems in which the variables are resricted to the values 0 and 1.
The text of many ACM TOMS algorithms is available online through ACM: http://www.acm.org/pubs/calgo or NETLIB: http://www.netlib.org/toms/index.html.
TOMS449 is available in a FORTRAN77 version.
You can go up one level to the FORTRAN77 source codes.