1. Pennsylvania geology Publication/Creation: [Harrisburg] : [Topographic and Geologic Survey, Dept. of Environmental Resources] Resource Type: Journal, Newspaper or Serial Access & Availability: Loading
2. Pennsylvania geology Publication/Creation: [Harrisburg] : [Topographic and Geologic Survey, Dept. of Environmental Resources] Resource Type: Journal, Newspaper or Serial Access & Availability: Loading
3. Progress report Publication/Creation: Harrisburg : Commonwealth of Pennsylvania, Dept. of Environmental Resources, Office of Resources Management, Bureau of Topographic and Geologic Survey Resource Type: Journal, Newspaper or Serial Access & Availability: Loading