Merrill, G. P. (1920). Contributions to a history of American State geological and natural history surveys. Government Printing Office.
Chicago-Zitierstil (17. Ausg.)Merrill, George P. Contributions to a History of American State Geological and Natural History Surveys. Washington: Government Printing Office, 1920.
MLA-Zitierstil (9. Ausg.)Merrill, George P. Contributions to a History of American State Geological and Natural History Surveys. Government Printing Office, 1920.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.