Agresti A. (2002). Categorical Data Analysis. John Wiley & Sons, Inc.,
Hoboken, NJ, USA. doi:10.1002/0471249688
Hunter D. R. (2004). The Annals of Statistics, 32(1), 384–406.
http://www.jstor.org/stable/3448514
Cragg, J. G., & Uhler, R. S. (1970). The Canadian Journal of
Economics 3(3), 386-406. doi:10.2307/133656
McFadden, D. (1973). Conditional logit analysis of qualitative choice behavior.