Hodges, John C.
Harcourt Brace Jovanovich, 1972
Buku Teks SO
Schorer, Mark
Harcourt, Brace Jovanovich, 1972
Buku Teks SO
Graham, Sheila Y.
Harcourt Brace Jovanovich , 1972
Buku Teks SO
Marius, Richard
McGraw-Hill, 1988
Buku Teks
Marius, Richard
McGraw-Hill, 1988
Buku Referensi