Population Demography 112 Population Economics 109 Statistics 61 Birth control 52 Congresses 40 Periodicals 35 more ... Economic aspects 34 Addresses, essays, lectures 32 Food supply 32 Agriculture 24 Emigration and immigration 24 Economic conditions 22 Sociology 22 Underdeveloped areas 22 Public health 21 Public Health 20 Aging 19 Migration 19 Social conditions 19 Mathematical models 18 Statistics, Vital 18 Population policy 17 Economic development 16 Social Policy 16 Social policy 16 Ecology 15 Labor Economics 15 Labor economics 15 Sociology, general 15 less ...