Skema, V. W., Sholes, M. A., & Edmunds, W. E. (1982). The economic geology of the Upper Freeport coal in northeastern Greene county, Pennsylvania. Pennsylvania Geological Survey.
Chicago Style (17th ed.) CitationSkema, V. W., Mark A. Sholes, and William E. Edmunds. The Economic Geology of the Upper Freeport Coal in Northeastern Greene County, Pennsylvania. Harrisburg: Pennsylvania Geological Survey, 1982.
MLA (9th ed.) CitationSkema, V. W., et al. The Economic Geology of the Upper Freeport Coal in Northeastern Greene County, Pennsylvania. Pennsylvania Geological Survey, 1982.
Warning: These citations may not always be 100% accurate.