APA (7e ed.) Bronvermelding

Não informado. (2001). Bulletin of the Pennsylvania Geological Survey. Pennsylvania Geological Survey.

Chicago (17e ed.) Bronvermelding

Não informado. Bulletin of the Pennsylvania Geological Survey. Harrisburg, Pa: Pennsylvania Geological Survey, 2001.

MLA (8e ed.) Bronvermelding

Não informado. Bulletin of the Pennsylvania Geological Survey. Pennsylvania Geological Survey, 2001.

Let op: Deze citaties zijn niet altijd 100% accuraat.