Dyfyniad APA
Urwellen, R. H. (2009). Oil spill costs and impacts. Nova Science Publishers, Inc..
Dyfyniad Arddull Chicago
Urwellen, Robert H. Oil Spill Costs and Impacts. New York: Nova Science Publishers, Inc., 2009.
Dyfyniad MLA
Urwellen, Robert H. Oil Spill Costs and Impacts. Nova Science Publishers, Inc., 2009.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.