Não informado. (2001). Bulletin of the Pennsylvania Geological Survey. Pennsylvania Geological Survey.
Citace podle Chicago (17th ed.)Não informado. Bulletin of the Pennsylvania Geological Survey. Harrisburg, Pa: Pennsylvania Geological Survey, 2001.
Citace podle MLA (8th ed.)Não informado. Bulletin of the Pennsylvania Geological Survey. Pennsylvania Geological Survey, 2001.
Upozornění: Tyto citace jsou generovány automaticky. Nemusí být zcela správně podle citačních pravidel..