"Natural Resource Economics" or just "Resource Economics"

Hi. I have been searching on the Internet the right expression, but I am not sure yet. I need to translate "Economía Ambiental y de Recursos Humanos". I found "Environmental and Natural Resource Economics" and "Environmental and Resource Economics", both in the site of reliable organizations. I would like to know what is the best expression in this case.  The second expression, just "Resource Economics" without "Natural" is not my favorite, I feel that "Natural" is required, however, I saw it in many sites, for instance:  http://www.eaere.org/  and http://enviro.colorado.edu/Ws/.

Thanks for your help. Nodding" src="http://www.englishforums.com/emoticons/emotion-79.gif" _width="19" _height="19"> 


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