Não informado. (1999). Missouri bureau of geology and mines. Tribune Printing.
Chicago-viite (17. p.)Não informado. Missouri Bureau of Geology and Mines. Jefferson City, Mo: Tribune Printing, 1999.
MLA-viite (8. p.)Não informado. Missouri Bureau of Geology and Mines. Tribune Printing, 1999.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.