by Royston M. Roberts ... [et al.]
Rinehart and Winston, 1969
Buku Teks
Fishel, Derry L., author
Macmillan, 1971
Buku Teks
Doyle, Michael P., author
John Wiley & Sons, 1980
Buku Teks
Dannley, Ralph L., author
Macmillan, 1968
Buku Teks
Kice, John L., author
New York Macmillan Publishing 1974,
Buku Teks