W.H. Van Schuur.(1984). Structure in Political Beliefs: A New Model for
Stochastic Unfolding with Application to European Party Activists. CT Press.
W.J. Post. (1992). Nonparametric Unfolding Models: A Latent Structure Approach. M
& T series. DSWO Press.
W.J. Post. and T.AB. Snijders (1993). Nonparametric unfolding models for dichotomous data. Methodika.