Bulletin. 486. Carbonizing properties, Pocahontas no. 6, Davy Sewell, and Fire Creek coals from West Virginia and Upper and Lower Kittanning and Upper and Lower Freeport coals from Pennsylvania [with list of Publications on survey of carbonizing properties of American coals]: by J. D. Davis, D. A. Reynolds, R. E. Brewer, D. E. Wolfson, B. W. Naugle, and G. W. Birge.