The northern Townships of Butler County part first - Chance, Henry Martyn 1856-1937 (Board of Commissioners for the Second Geological Survey, 1879)
Band 1 (Report of progress 1878) und 2 (Report of progress 1875) in einem Band
Karten-Beilagen: Geological map of Northern Butler (1 Blatt); Map of the Allegheny Valley, near Parker, in Armstrong and Butler Counties (1 Blatt); Outline map, showing the minor Axes of the sixth bituminous coal basin (1 Blatt); Valleys of the Beaver and Shenango Rivers and Slippery Rock Creek (1 Blatt); Oil well records and surface sections (1 Blatt); Profile section from Homewood to Sharon (1 Blatt)