Spurr, Josiah Edward, 1870-1950. Geology of the Aspen mining district, Colorado, with atlas. - Washington, Govt. print. off., 1898. - 260 p. LCCN: gs 05000816 Subjects--Topical Terms: Geology--Colorado.Silver mines and mining--Colorado. LC Class. No.: QE75 / .M7 vol. 31 Gov. Doc. Class. No.: I 19.9:31