@article{Manfreda2006,
author = {Manfreda, K.L. and Batagelj, Z. and Vehovar, V.},
title= {Design of web survey questionnaires: Three basic experiments},
year = {2006},
doi = {10.1111/j.1083-6101.2002.tb00149.x},
volume = {7},
number = {3},
pages = {731},
}