Legislative history of Federal coal mine health and safety act of 1969 (Public law 91-173) as amended through 1974, including black lung amendments of 1972; Aug. 1975. pt.2. Appendix: app.1, Black lung legislation as amended through 1972; app.2. Senate related bills on Federal coal mine health and safety act of 1969; app.3, Excerpts from bound Congressional record daily digest for 1969.