BibTeX

@incollection{ encycyApprox08,
     author = {Thomas Bittner and John G. Stell},
     title = {Approximation},
     booktitle = {Encyclopedia of GIS},
     year = {2008},
     pages = {21-25},
     ee = {http://dx.doi.org/10.1007/978-0-387-35973-1_65},
     editor = {Shashi Shekhar and Hui Xiong},
     publisher = {Springer},
     year = {2008},
     isbn = {978-0-387-30858-6},
     leeds = {true}
}