Gaya APA

Leffler, W, L. (2009). Petroleum refining in nontechnical Language I : History, oil patch to reefinery, crude oil (4). New York: .

Gaya MLA

Leffler, William, L.. "Petroleum refining in nontechnical Language I : History, oil patch to reefinery, crude oil". 4 New York: , 2009. Multimedia.