1. An, M.Y., Ayala, R.A., 1996. A Mixture Model of Willingness to Pay Distributions, Mimeograph, available by FTP at http://www.pub/man/papers/npecross.ps.
2. Artuso, A., 1996. Creating Linkages between Valuation, Conservation and Sustainable Development of Genetic Resources, proceedings of the Symposium “Economics of Valuation and Conservation of Genetic Resources for Agriculture”, 13–15 May 1996, Rome, Italy, Università degli Studi Tor Vergata.
3. Welfare measurement using contingent valuation: a comparison of techniques;Boyle;American Journal of Agricultural Economics,1988
4. Cicia, G., Scarpa, R., 2000. Willingness to pay for rural landscape preservation: a case study in Mediterranean agriculture. Nota di lavoro 59. Fondazione Enrico Mattei.
5. Cooper, J.C., Hanemann, W.M., Signorello, G., 2001. One-and-one half bound dichotomous choice contingent valuation, working paper n. 921, AREC University of California, Berkeley, http://are.berkeley.edu/∼hanemann/oohpap1.pdf.