STAFF USBM I C 8335 POTEN SOURCES OF ALUM 1967IND GEOL SUR C 266 COAL RESOURCES OF IND 1953USGS B 708 HIGH GRADE CLAYS OF THE EASTERN US 1922IND. GEOL. SUR. REPT. OF PROGRESS NO. 11 PA. UNDERCLAYS.PETERS FRANK A ET AL BUMINES R I 6927 1967PETERS FRANK A AND PAUL W JOHNSON BUMINES I C 8648 1974BUMINES TECHNICAL PAPER 417 ANALYSES OF INDIANA COALS