Molly Andrews, Corinne Squire, Maria Tamboukou, editor
Sage, 2009
Buku Teks
Viswanathan, Madhu, author
SAGE Publ., 2005
Buku Teks
Judd, Charles M., author
Methuen, 1991
Buku Teks
Louise H. Kidder
Holt, Rinehart and Winston, 1981
Buku Teks
Lee, Raymond M., author
Open University Press, 2000
Buku Teks SO