Starr, Cecie
Brooks/Cole, 2012
Buku Teks SO
Inglis, J.K.
Pergamon Press , 1974
Buku Teks
Silverthorn, Dee Unglaub
Pearson, 2016
Buku Teks SO
Mader, Sylvia S.
McGraw-Hill, 2000
Buku Teks SO
Mader, Sylvia S.
[publisher not identified], [date of publication not identified]
Buku Teks SO