Welch, Joseph N.
Houghton Miffiln, 1956
Buku Teks SO
Park, Won
Inka University Press, 1970
Buku Teks SO
Pringle, John Martin Douglas, 1912-
Angus and Robertson, 1971
Buku Teks SO
Matsushita, Konosuke
PHP Institute International, 1982
Buku Teks SO
Zweig, Arnold
A Primier Book, 1959
Buku Teks SO