Pickering, J. C. Cost Keeping for Small Metal Mines. [Washington D.C.]. UNT Digital Library. http://digital.library.unt.edu/ark:/67531/metadc66479/. Accessed April 23, 2014.
Note: Inconsistencies in capitalization and punctuation within the Digital Library may affect this citation. Before using this citation in formal writing, please consult your preferred style manual. More information.