Merrifield, Ralph
The Pitman Pres , 1983
Buku Teks
Stair, Lila B.
Lincolnwood Illinois VEM Career Horizons , 1992
Buku Teks
Stuart, Peter C.
Far horizon books, 1989
Buku Teks
Barclay, Dorothy, 1918-
Collier Books, 1959
Buku Teks
Patel, R. C.
Charya Book Depot, 1978
Buku Teks