Schäfer, R. (2007). Climate, Water Supply, Energy and Food: Challenges for the future. Topos.
Chicago-referens (17:e uppl.)Schäfer, Robert. "Climate, Water Supply, Energy and Food: Challenges for the Future." Topos 2007.
MLA-referens (8:e uppl.)Schäfer, Robert. "Climate, Water Supply, Energy and Food: Challenges for the Future." Topos, 2007.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.