edited by Charles W. Finkl, Jnr.
Van Nostrand Reinhold, 1984
Buku Referensi
North, Adrian C., author
Oxford, 2008
Buku Teks
Nicolson, Paula, author
MacMillan Education, 1986
Buku Teks
Snowman, Jack, author
Wadsworth and Cengage Learning, 2012
Buku Teks
Blackwell Publishing Limited, 2001
Majalah, Jurnal, Buletin