Cherkin DC, Grothaus L, Wagner EH. The effect of office visit copayments on preventive care services in an HMO. Inquiry. 1990 Spring;27(1):24-38.
Cherkin DC, Grothaus L, Wagner EH. The effect of office visit copayments on preventive care services in an HMO. Inquiry. 1990 Spring;27(1):24-38.