EXPLORATION AND DEVELOPMENT OF COAL RESOURCES 1970-1975 = EXPLORATION ET DEVELOPPEMENT DE RESSOURCES DE CHARBON PENDANT LA PERIODE 1970-75RISSER HE.1973; QUART. COLORADO SCH. MINES; U.S.A.; DA. 1973; VOL. 68; NO 2; PP. 75-79Serial Issue

THE U.S. ENERGY DILEMMA: THE GAP BETWEEN TODAY'S REQUIREMENTS AND TOMORROWS POTENTIAL.RISSER HE.1973; ILLINOIS STATE GEOL. SURV., ENVIRONMENT. GEOL. NOTES; USA; 1973, NUM. 0064, P. 1 A 64Serial Issue

ECONOMICS OF THE MINERAL INDUSTRIES.VOGELY WA; RISSER HE; BUCK WK et al.1976; NEW YORK; A.I.M.E.; DA. 1976; PP. (863P.); BIBL. DISSEM.Book