Nomograph for Calculating Mineral-Matter-Free Coal Analyses Based on Parr Formulas, 1939

Nomograph for Calculating Mineral-Matter-Free Coal Analyses Based on Parr Formulas, 1939, Folder: 16. Robert W. Craigo, Collector, Geological, Topographical, and Other Maps of West Virginia, A&M 2622. West Virginia and Regional History Center. https://archives.lib.wvu.edu/repositories/2/archival_objects/170543 Accessed April 30, 2026.