Wenzhong Shi Chui Kwan Cheung Changqing Zhu Modelling error propagation in vector-based buffer analysis. 251-271 2003 17 International Journal of Geographical Information Science 3 http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=1365-8816&volume=17&issue=3&spage=251 db/journals/gis/gis17.html#ShiCZ03