Smith VK, Evans MF, Banzhaf HS, Poulos C. Can weak substitution be rehabilitated? Environ Resour Econ (Dordr). 2010 Feb 1;45(2):203-21.
Garcia-Albeniz X, Martinez-Fernandez A, Gascon P. Combining targeted therapies. Target Oncol. 2007 Oct;2(4):241-52. doi: 10.1007/s11523-007-0062-5
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.