Galvin, Kathleen M.
Scott, Foresman and Company , 1982
Buku Teks SO
Ballinger Publishing Company, 1986
Buku Teks SO
Dyere, Everett D.
McGraw-Hill, 1979
Buku Teks SO
Kidman, Antony
Biochemical & General Services, 1995
Buku Teks SO
Lubis, Junisi Renatha
Fakultas Psikologi Universitas Indonesia, 2012
UI - Skripsi Open