Franzini L, White C, Taychakhoonavudh S, Parikh R, Zezza M, Mikhail O. Variation in inpatient hospital prices and outpatient service quantities drive geographic differences in private spending in Texas. Health Serv Res. 2014 Dec;49(6):1944-63. doi: 10.1111/1475-6773.12192
Smith VK, Evans MF, Banzhaf HS, Poulos C. Can weak substitution be rehabilitated? Environ Resour Econ (Dordr). 2010 Feb 1;45(2):203-21.
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.