Artikel Jurnal
Key, Mary Ritchie, author
Tubingen Gunter Narr Verlag 1979
Buku Teks
Holzberlein, Deanne, author
The Haworth Press, 1988
Buku Teks
Fletcher, Sydney E., author
Grosset & Dunlap, 1954
Buku Teks
edited by Martin D. Joachim
The Haworth Press, 1993
Buku Teks