Davis KL, Mitra D, Medjedovic J, Beam C, Rustgi V. Direct economic burden of chronic hepatitis c virus in a United States managed care population. J Clin Gastroenterol. 2011 Feb 1;45(2):e17-24.
Reed (Earnshaw) SJ, Reed JH. The use of statistical quality control charts in monitoring interviewers. Proceedings of the Survey Research Methods Section, American Statistical Association. 1997 Jan;893-8.