1. An Historical Review of the Gravity and Potential Concepts of Human Interaction
2. J. E. Hobbs, and E. R. Woolmington, 1966 :Water Availability as a Limiting Factor in Decentralised Urban Development.University of New England, Research Series in Applied Geography, No. 2.
3. Defining and Estimating a Trading Area
4. J. C. Kilborne, 1960 :An Examination of the Interaction of Urban Fields in the Namoi Basin. M.A. Thesis , University of New England.
5. L. Killion, 1967 :Functional Integration in the Tweed Valley, N.S.W.University of New England, Research Series in Applied Geography, No. 11.