Bandhu, Vishva, author
The V. V. Institute, 1956
Buku Referensi
International Society for Educational Information
ISEI, 1987
Buku Teks
Virtue and Company Limited , 1977
Buku Teks
Bellman, Richard, author
Academic Press, 1973
Buku Teks
Alonso, Marcelo, 1921-, author
Addison-Wesley, 1967
Buku Teks