Smykey, Edward W.
Macmillan, 1961
Buku Teks
James A. Tompkins, Dale A. Harmelink [editors]
McGraw-Hill, 1994
Buku Referensi
Constantin, James A.
Appleton-Century-Crofts, 1966
Buku Teks
edited by Martin Chritopher and Gordon Wills
George Allen and Unwin, 1972
Buku Teks
Jones, james V.
McGrawHill, 1994
Buku Referensi