@inbook{Vehovar2016,
author = {Vehovar, V. and Toepoel, V. and Steinmetz, S.},
title= {Non-probability sampling},
year = {2016},
doi = {10.4135/9781473957893.n22},
editor = {Wolf, C.},
editor = {Joye, D.},
editor = {Smith, T.W.},
editor = {Fu, Y.},
booktitle = {The SAGE handbook of survey methodology},
address = {London},
publisher = {SAGE},
pages = {329--345},
}