APA (7e ed.) Bronvermelding

Não informado. (2004). Environmental geology notes. Illinois State Geological Survey.

Chicago (17e ed.) Bronvermelding

Não informado. Environmental Geology Notes. Naperville, Ill: Illinois State Geological Survey, 2004.

MLA (8e ed.) Bronvermelding

Não informado. Environmental Geology Notes. Illinois State Geological Survey, 2004.

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