@inbook{Poorthuis2016,
author = {Poorthuis, A. and Zook, M. and Shelton, T. and Graham, M. and Stephens, M. },
title= {Using geotagged digital social data in geographic research},
year = {2016},
editor = {Clifford, N.},
editor = {Cope, M.},
editor = {Gillespie, T.},
editor = {French, S. },
booktitle = {Key methods in geography},
address = {Los Angeles},
publisher = {Sage},
pages = {248--269},
}