Papp, A. R., Hower, J. C., & Peters, D. C. Atlas of coal geology. AAPG.
Chicago Style (17th ed.) CitationPapp, Alexander R., James C. Hower, and Douglas C. Peters. Atlas of Coal Geology. [S.l.]: AAPG.
MLA (8th ed.) CitationPapp, Alexander R., et al. Atlas of Coal Geology. AAPG.
Warning: These citations may not always be 100% accurate.