Gaya APA

Schaefer, C. (1989). U.S.A. Oilfield Service, Supply, Manufacturers : Directory . Tulsa: Pennwell Pubishing Company.

Gaya MLA

Schaefer, Carol. "U.S.A. Oilfield Service, Supply, Manufacturers : Directory". Tulsa: Pennwell Pubishing Company, 1989. Buku PPs Prodi Teknik Kimia.