History 18 Description and travel 17 Maps 17 Real property 17 Museums 16 Associations, institutions, etc 13 Directories 13 more ... Societies 13 Local transit 12 Societies, etc 10 Business enterprises 9 Economic conditions 7 Ethnic groups 7 Periodicals 6 Railroads 6 Vietnamese Americans 6 Mafia 5 Rents--Pennsylvania--Philadelphia Metropolitan Area 5 Street-railroads 5 Transportation 5 Central business districts 4 Commerce 4 Commuting traffic 4 Ethnic relations 4 Korean Americans 4 Regional planning 4 Social registers 4 Special libraries 4 Asian Americans 3 Guidebooks 3 Historic buildings 3 Library cooperation 3 Roads 3 Streets 3 Suburbs 3 Vietnamese periodicals 3 Américains d'origine asiatique 2 Américains d'origine vietnamienne 2 Archives 2 Bicycle touring 2 less ...