Gandhi, M.K.
Ahmedabad Navajivan Publishing House 1951
Buku Teks
Gendt, M.C.E. van
Krips Repro, 1980
Buku Teks
Noor, Abdun, author
World Bank, 1981
Buku Teks
Meredith, William M., author
McGraw-Hill , 1967
Buku Teks
Dignan, Mark B., author
Lea & Febiger, 1981
Buku Teks