"Anthracite in the Lehigh region of Pennsylvania, 1820-45."; "Hoffman, John Nathan."; "Anthracite coal--Pennsylvania--Lehigh River Valley."; "Hoffman, John Nathan."; "1968"; "

Serial issue. Issued as: Uinited States. National Museum. Bulletin, 252. Also issued as: Contributions from the Museum of History and Technology, paper 72.

"; ""; "P12603"; "pec"; "Anthracite coal--Pennsylvania--Lehigh River Valley."; "14256"; .