Pratt, W. P. (1995). The Midcontinent strategic and critical minerals project. US Geological Survey circular 1124.
Chicago ZitierstilPratt, Walden P. "The Midcontinent Strategic and Critical Minerals Project." US Geological Survey Circular 1124 1995.
MLA ZitierstilPratt, Walden P. "The Midcontinent Strategic and Critical Minerals Project." US Geological Survey Circular 1124 1995.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.