Não informado. (2009). Occasional Publications of the Department of Geography. University of Illinois at Urbana-Champaign.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Occasional Publications of the Department of Geography. Urbana, Ill: University of Illinois at Urbana-Champaign, 2009.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Occasional Publications of the Department of Geography. University of Illinois at Urbana-Champaign, 2009.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.