Wetherell, D.F., author
IKIP Press, 1976
Buku Teks
Wetherell, D.F., author
IKIP Semarang Press, [date of publication not identified]
Buku Referensi
edited by J. Reinert and Y.P.S. Bajaj
Narosa Publishing , 1989
Buku Teks
Narayanaswamy, S., author
Tata McGraw-Hill, 1994
Buku Teks
Artikel Jurnal