Gupta, G.P.
Publishing House , 1959
Buku Teks
edited by Kiyoshi Funatani, George E.Totten
ASM International, 2000
eBooks
Washington, D.C. World Bank 1999,
Buku Teks
Thorp, Willard L., author
John Hopkins Press, 1954
Buku Teks
New York National Bureau of Economic Research, 1947 c.1943,
Buku Teks