1. The Cambrian rocks of Pennsylvania Author/Creator: Walcott, Charles D. 1850-1927, (Charles Doolittle), author Publication/Creation: Washington, D.C. : Department of the Interior, United States Geological Survey, 1896 Resource Type: Book Access & Availability: Loading
2. Correlation papers : Cambrian Author/Creator: Walcott, Charles D. 1850-1927, (Charles Doolittle), author Publication/Creation: Washington, D.C. : Department of the Interior, United States Geological Survey, 1891 Resource Type: Book Access & Availability: Loading