Liebing, Ralph W., author
John Wiley & Sons, 1983
Buku Teks
Beguin, Sylvie, author
Fratelli Fabbri, 1970
Buku Referensi
Nabila Putri Utami, author
Fakultas Psikologi Universitas Indonesia, 2017
UI - Skripsi (Membership)
Maps Com, 2007
Buku Referensi
Sato, G. Takeshi, author
Pradnya Paramita; balai pustaka, 1981
Buku Teks