Urban N, Anderson GL, Tseng A. Effects on response rates and costs of stamps vs business reply in a mail survey of physicians. J Clin Epidemiol. 1993 May;46(5):455-9.
Urban N, Anderson GL, Tseng A. Effects on response rates and costs of stamps vs business reply in a mail survey of physicians. J Clin Epidemiol. 1993 May;46(5):455-9.