Conservation of natural resources Recursos naturales 17 Foreign relations 16 Integración regional 16 Política exterior 16 Publicaciones periódicas 16 Environmental protection 8 Conservation des ressources naturelles 6 Ecology 5 Environmental policy 4 Environnement 4 Law and legislation 4 Nature conservation 4 Conservación de los recursos naturales 3 Environmental law 3 Nature 3 Pollution 3 Protection 3 Conservation 2 Derecho y legislación 2 Ecologie 2 Economic aspects 2 Environmental Pollution 2 Human ecology 2 Research 2 Trials 2 Trials, litigation, etc 2 42.00 biology: general 1 Applied ecology 1 Aspect e ́conomique 1