english: For other approaches to weighting web surveys, see Schonlau et al. (2009), Valliant and Dever (2011), and Bethlehem (2010).
non_english: Alang sa ubang pamaagi sa kabug-aton web survey, tan-awa Schonlau et al. (2009) , Valliant and Dever (2011) , ug ang Bethlehem (2010) .