Proceedings of a symposium - Ritchie, Joe T.; Jones, James W.; Tsuji, Gordon Y.; Hildebrand, Peter; Rosenzweig, Cynthia; Allen, Leon Hartwell, Jr.; Harper, Lowry A.; Hollinger, Steven E.; Jones, James W.; Peterson, Gary A.; Kral, David M.; Viney, Marian K. (ASA Special publication, 1995)