APA (7e ed.) Bronvermelding

Não informado. (1931). Mineral Industries. Pennsylvania State College, College of Earth and Mineral Sciences.

Chicago (17e ed.) Bronvermelding

Não informado. Mineral Industries. State College, Pa: Pennsylvania State College, College of Earth and Mineral Sciences, 1931.

MLA (8e ed.) Bronvermelding

Não informado. Mineral Industries. Pennsylvania State College, College of Earth and Mineral Sciences, 1931.

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