Ashley, G. H. (1933). The undeveloped mineral resources of Pennsylvania. Department of internal affairs, Topographic and geologic survey.
Chicago Style (17th ed.) CitationAshley, Geo. H. The Undeveloped Mineral Resources of Pennsylvania. Harrisburg, Pa.: Department of internal affairs, Topographic and geologic survey, 1933.
MLA (9th ed.) CitationAshley, Geo. H. The Undeveloped Mineral Resources of Pennsylvania. Department of internal affairs, Topographic and geologic survey, 1933.
Warning: These citations may not always be 100% accurate.