Smith VK, Evans MF, Banzhaf HS, Poulos C. Can weak substitution be rehabilitated? Environ Resour Econ (Dordr). 2010 Feb 1;45(2):203-21.
Espaulella J, Guyer H, Diaz-Escriu F, Mellado-Navas JA, Castells M, Pladevall-Vila M. Nutritional supplementation of elderly hip fracture patients. A randomized, double-blind, placebo-controlled trial. Age Ageing. 2000 Sep;29(5):425-31.
Mansfield CA. Despairing over disparities: an empirical analysis of the relationship between willingness-to-pay and willingness-to-accept. Environ Resour Econ (Dordr). 1999;13(2):219-34.