Leong,Goh Cheng Morgan Gillian C. (1972). A systematic approach to human and economic geography: With special reference to East and Southeast Asia and Australasia (2nd.Ed.). Oxford University Press.

Leong,Goh Cheng Morgan Gillian C. A Systematic Approach to Human and Economic Geography: With Special Reference to East and Southeast Asia and Australasia. 2nd.Ed. New York: Oxford University Press, 1972.

Leong,Goh Cheng Morgan Gillian C. A Systematic Approach to Human and Economic Geography: With Special Reference to East and Southeast Asia and Australasia. 2nd.Ed. Oxford University Press, 1972.