1. Esri 2014 How Original Huff Model Works http://resources.arcgis.com/en/help/main/10.2/#/How_Original_Huff_Model_works/00mm0000004w000000/
2. Spatial accessibility of primary care: Concept, methods and challenges;Guagliardo;International Journal of Health Geographics,2004
3. How accessibility shapes land use;Hansen;Journal of the American Institute of Planners,1959
4. Huff D L McCallum B M 2008 Calibrating the Huff Model http://www.esri.com/library/whitepapers/pdfs/calibrating-huff-model.pdf