1. The Cambrian rocks of Pennsylvania Author/Creator: Walcott, Charles D. 1850-1927. (Charles Doolittle) Publication/Creation: Washington : Govt. Print. Off, 1896 Resource Type: Book Is Part Of: U.S. Geological Survey bulletin, no. 130-136. Access & Availability: Loading
2. 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
3. Correlation papers ; Cambrian Author/Creator: Walcott, Charles D. 1850-1927. (Charles Doolittle) Publication/Creation: Washington : Govt. Print. Off, 1891 Resource Type: Book Is Part Of: U.S. Geological Survey bulletin, no. 81-83. Access & Availability: Loading
4. 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