1. BIRKIN , M. , CLARKE , G. P. , CLARKE , M. , and WILSON , A. C. , 1987 , Geographical information systems and model-based locational analysis: ships in the night or the beginnings of a relationship? In Working Paper 498 ( Leeds : School of Geography ).
2. How to Eliminate Certain Defects of the Potential Formula
3. FOURTH MEMORANDUM (1988–1990) , The Fourth Memorandum on Physical Planning (Extra) Part A/B/C/D: On the Road to 2015 . Ministry of Housing, Physical Planning and the Environment ( The Hague : Staatsuitgeverij ).