Não informado. (2009). Occasional Publications of the Department of Geography. University of Illinois at Urbana-Champaign.
Chicago-referens (17:e uppl.)Não informado. Occasional Publications of the Department of Geography. Urbana, Ill: University of Illinois at Urbana-Champaign, 2009.
MLA-referens (8:e uppl.)Não informado. Occasional Publications of the Department of Geography. University of Illinois at Urbana-Champaign, 2009.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.