Stallwitz, Anke
Springer, 2012
eBooks
Moore, Robert
Routledge & Kegan Paul, 1982
Buku Teks SO
Firth, Jack
The Ramsay Head Press, 1979
Buku Teks SO
Fakultas Ilmu Pengetahuan Budaya Universitas Indonesia, 1976
UI - Skripsi Membership
Fry, Peter Somerset
Routledge , 2001
Buku Teks SO