Natural resources 333 Conservation of natural resources 64 Natural Resource Economics, (New March 2000) 58 Sustainable development 49 Economics 43 Environmental policy 43 India 37 Sustainability 37 Natural resource management 30 Policy and Planning 26 Environmental economics 25 Tourism and Travel 23 Human ecology 22 Social Psychology and Social Anthropology, (New March 2000) 22 Agriculture 21 Environmental protection 21 Management 21 Biodiversity 20 Leisure, Recreation and Tourism Economics, (New March 2000) 20 Natural Resources 19 Pollution 19 natural resources 19 Agricultural Economics 17 Economic development 17 Environmental impact 17 Case studies 16 Ecology 16 Environmental management 16 Land Resources 16 Land use 16