Swartz, Clifford E.
John Wiley & Sons, 1981
Buku Teks
Schmidt, Erich W.
Pergamon Press , 1974
Buku Teks
Hasugian, Rudy
Universitas Indonesia, 2007
UI - Skripsi (Membership)
McCarthy, Francis W.
Allyn and Bacon, 1972
Buku Teks
Swenson, Hugo N.
John Wiley & Sons, 1957
Buku Teks