Natural resources 333 Conservation of natural resources 64 Natural Resource Economics, (New March 2000) 58 Economics 54 Sustainable development 54 Environmental policy 46 India 39 Sustainability 37 Environmental economics 33 Natural resource management 30 Agriculture 29 Ecology 27 Human ecology 27 Policy and Planning 26 Economic development 24 Management 24 Biodiversity 23 Tourism and Travel 23 Social Psychology and Social Anthropology, (New March 2000) 22 Environmental protection 21 Leisure, Recreation and Tourism Economics, (New March 2000) 20 Environmental management 19 Land use 19 Natural Resources 19 Pollution 19 natural resources 19 Agricultural Economics 17 Environment 17 Environmental impact 17 Social Sciences 17