History Sources 17 Archives 6 Politics and government 6 Social life and customs 6 Description and travel 4 Indians of North America 4 more ... Societies, etc 4 African Americans 3 Anthracite coal industry 3 Antiquities 3 Bibliography 3 Coal mines and mining 3 Fortification 3 Historic buildings 3 Minorities 3 Oral history 3 Petroleum industry and trade 3 Study and teaching 3 Administration 2 Anniversaries 2 Anniversaries, etc 2 Architecture, Harmonist 2 Biography 2 Capital and capitol 2 Coal miners 2 Collective settlements 2 Education 2 Emigration and immigration 2 Ethnology 2 Frontier and pioneer life 2 Historical markers 2 Indexes 2 Industries 2 Interviewing 2 Militia 2 Photographers 2 Religious communities 2 Social conditions 2 Study skills 2 less ...