edited by R.J. Johnston, Derek Gregory, Geraldine Pratt, Michael Watts
Blackwell Publishing, 2000
Buku Referensi
edited by William Dodge Lewis, Henry Seidel Canby, Thomas Kite Brown
John C. Winston, 1942
Buku Referensi
Papalia, Diane E., author
McGraw-Hill, 2001
Buku Teks
Merriam-Webster, 2004
Buku Referensi
Macmillan, 1994
Buku Referensi