Gaya APA

Leffler, W, L. (2009). Petroleum refining in nontechnical language 5 : Catalytic cracking, Alkylation (4). New York: Penwell.

Gaya MLA

Leffler, William, L.. "Petroleum refining in nontechnical language 5 : Catalytic cracking, Alkylation". 4 New York: Penwell, 2009. Multimedia.