Weiss, Edda
McGraw-Hill, 1986
Buku Teks SO
Saunders, Joy
Pearson Education, 1994
Buku Teks SO
Jones, Randall L.
New York : Routledge , 2006
Buku Referensi
Donaldson, Bruce
Routledge, 2004
Buku Referensi
Anderfen, Hans Criftian
London DC Heath [t.th.]
Buku Teks