Audas, James Wales
Whitcombe & Tombs, 1947
Buku Teks
Sogang University, 2004
Buku Teks
Diekelmann, John, author
New York: McGraw-Hill, 1982
Buku Teks
Diekelmann, John, author
New York: McGraw-Hill, 1982
Buku Teks
Ciardi, John, author
Harper & Row , 1980
Buku Referensi