Dzhafarov, E. N. and Colonius, H. (2006) Reconstructing
  distances among objects from their discriminability.
  Psychometrika, 71, 365--386.  Dzhafarov, E. N. and Colonius, H. (2007) Dissimilarity
  cumulation theory and subjective metrics. Journal of
  Mathematical Psychology, 51, 290--304.
  Uenlue, A. and Kiefer, T. and Dzhafarov, E. N.
  (2009) Fechnerian scaling in R: The package fechner.
  Journal of Statistical Software, 31(6), 1--24.
  URL http://www.jstatsoft.org/v31/i06/.