Crocker, Mary E. Coffman, author
Erlangga, 2005
Buku Teks
Kurbegov, Eliane
Mc Graw Hill, 2012
Buku Teks
Henderson, Harold Gould, author
George Allen and Unwin, 1945
Buku Teks
Dobson, Kate, author
Berlitz, 1994
Buku Teks
Mont, Francis M Du
Barnes & Noble , 1947
Buku Teks