Goh, Phai Cheng
Citizenship laws of Singapore / Goh Phai Cheng
Educational Publications Bureau, 1970
 Buku Teks
Wheeler, James O.
Economic geography
John Wiley & Sons, 1986
 Buku Teks
Alexander, John W.
Economic geography
Prentice-Hall, 1979
 Buku Teks
Hartshorn, Truman Asa
Economic geography
Prentice-Hall, 1988
 Buku Teks
Thatcher, W.S.
Economic geography
English University Press, 1957
 Buku Teks