1. Caplin, P., and Nalebuff, B. 1986. Multidimensional product differentiation and price competition. Oxford Economic Papers 38.
2. Cubbin, J. 1975. Quality change and pricing behaviour in the United Kingdom car industry 1956–68. Economica 42: 43–58.
3. Domencich, T.A., and D. McFadden. 1975. Urban travel demand. Amsterdam: North Holland.
4. Gorman, W.M. 1956. A possible procedure for analysing quality differentials in the egg market. Journal paper No. 3129, Iowa Agricultural Experiment Station, and Review of Economic Studies (1980) 47: 843–856.
5. Hausman, J., and D. Wise. 1978. A conditional probit model for qualitative choice: Discrete decisions recognising interdependence and heterogeneous preferences. Econometrica 46: 403–426.