Agriculture Economic aspects 1,170 History 277 Agriculture and state 187 Research 176 Periodicals 169 Economic conditions 134 Land tenure 107 Rural conditions 104 Food supply 99 Congresses 90 Experimentation 54 Statistics 47 Rural development 44 Peasantry 43 Land use 39 Farm management 38 Produce trade 36 Agricultural innovations 35 Accounting 33 Land reform 33 Industries 31 Agricultural experiment stations 28 Agricultural laborers 28 Case studies 26 Agricultural industries 25 Mathematical models 25 Livestock 24 Social conditions 24 Societies, etc 24