@article{Elwood2012,
author = {Elwood, S. and M.J., Goodchild and Sui, D.},
title= {Researching Volunteered Geographic Information: Spatial data, geographical research, and new social practice},
year = {2012},
doi = {10.1080/00045608.2011.595657},
journal = {Annals of the Association of American Geographers},
volume = {102},
number = {3},
pages = {571--590},
}