Butler, Bert Sylvenus (1877-1960) United States of America. Geological Survey.
Butler, Bert Sylvenus (1877-1960) Loughlin, Gerald Francis (1880-1946) United States of America. Geological Survey.
Butler, Bert Sylvenus (1877-1960) Gale, Hoyt Stoddard (1876-1952) United States of America. Geological Survey.
Butler, Bert Sylvenus (1877-1960) Vanderwilt, John W. (1898-1992) Henderson, Charles W. (1885-?) United States of America. Geological Survey.
Butler, Bert Sylvenus (1877-1960) Heikes, Victor Conrad(1867-1948) Stany Zjednoczone. Geological Survey Heikes, V. C. Autor