Não informado. (1973). Journal of research of the United States Geological Survey. U.S. Geological Survey.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Journal of Research of the United States Geological Survey. Washington: U.S. Geological Survey, 1973.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Journal of Research of the United States Geological Survey. U.S. Geological Survey, 1973.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.