Williams, Sara

Penguin , 1993

 Buku Teks

Boxill, Roger

Macmillan, 1994

 Buku Teks SO

F. Gary Cunningham, Norman F. Gant, Kenneth J. Leveno, Larry C. Gilstrap III, John C. Hauth, Katharine D. Wenstrom, editor

McGraw-Hill, 2001

 Buku Referensi

Pritchard, Jack A.

Airlangga University , 1991

 Buku Teks SO

editors, Kenneth Kaushansky, Marshall A. Lichtman, Josef T. Prchal, Marcel Levi, Oliver W. Press, Linda J. Burns, Michael A. Caligiuri.

McGraw-Hill Education, 2016

 Buku Teks SO