Cipolla, Carlo M., author
Penguin, 1974
Buku Teks
Heimann, Eduard
Oxford University Press, 1959
Buku Teks
Roll, Eric
Prentice-Hall, 1959
Buku Teks
Naerssen, Frits Herman van, author
E.J. Brill, 1977
Buku Teks
Australia : Oxford University Press
Majalah, Jurnal, Buletin