Groenwold R, Uddin M, Roes K, de Boer A, Rivero-Ferrer E, Martin E, Gatto N, Klungel O. Instrumental variable analysis in randomized trials with non-compliance and observational pharmacoepidemiologic studies. OA Epidemiology. 2014 May 9;2(1):9.
Freund DA, Hurley RE, Adamache KW, Mauskopf J. The performance of urban and public hospitals and NHCs (neighborhood health centers) under Medicaid capitation programs. Hosp Health Serv Adm. 1990 Jan 1;35(4):525-46.