Gaya APA
Leffler, W, L. (2010).
Petroleum refining in nontechnical language 7 : Residual Reduction .
Tulsa,Oklahoma:
PennWell Corporation.
Gaya MLA
Leffler, William, L..
"Petroleum refining in nontechnical language 7 : Residual Reduction".
Tulsa,Oklahoma:
PennWell Corporation,
2010.
Multimedia.