Dennis, Lorraine Bradt, author
WB. Saunders, 1967
Buku Teks
Holdsworth, Ruth, author
Macmillan, 1982
Buku Teks
Kalish, Richard A., author
Wadsworth, 1966
Buku Teks
Munn, Norman L., author
Houghton-Mifflin, 1955
Buku Teks
Lindgran, Henry Clay
John Wiley & Sons, 1966
Buku Teks