Mohammad Aries
1987
UI - Skripsi Membership
Sulistyo-Basuki
Sagung Seto, 2012
Buku Referensi
Perpustakaan Nasional RI, 2002
Multimedia
Paula Umboh
1998
UI - Tesis Membership
Eaton, Kay
Dewan Bahasa dan Pustaka, Kementerian Pelajaran Malaysia, 1981
Buku Teks SO