http://www.dmoz.org/Science/Environment/
http://www.dmoz.org/Regional/Europe/Greece/Science_and_Environment/
http://www.dmoz.org/Society/Law/Legal_Information/Environmental_Law/
http://www.dmoz.org/Science/Environment/Air_Quality/
http://www.dmoz.org/Science/Environment/Pollution_Prevention_and_Recycling/
http://www.dmoz.org/Science/Social_Sciences/Economics/Environmental_Economics/
http://www.dmoz.org/Science/Environment/Ozone_Layer/
http://www.dmoz.org/Science/Environment/Energy/
http://www.wwf.org/
http://www.unep.org/climatechange/