Não informado. (1967). Earth and Mineral Sciences. Pennsylvania State College, College of Earth and Mineral Sciences.
Chicago (17e ed.) BronvermeldingNão informado. Earth and Mineral Sciences. University Park, Pa: Pennsylvania State College, College of Earth and Mineral Sciences, 1967.
MLA (8e ed.) BronvermeldingNão informado. Earth and Mineral Sciences. Pennsylvania State College, College of Earth and Mineral Sciences, 1967.
Let op: Deze citaties zijn niet altijd 100% accuraat.