Gaya APA

Leffler, W, L. (2009). Petroleum refining in nontechnical language 6 : Hydrocracking, Isomerization (4). New York: PennWell B.

Gaya MLA

Leffler, William, L.. "Petroleum refining in nontechnical language 6 : Hydrocracking, Isomerization". 4 New York: PennWell B, 2009. Multimedia.