Andronis L, Oppong RA, Manga N, Senanayake E, Gopal S, Charman S, Giri R, Luckraz H. Is the Venner-PneuX endotracheal tube system a cost-effective option for post cardiac surgery care? Ann Thorac Surg. 2018 Sep;106(3):757-63. doi: 10.1016/j.athoracsur.2018.03.058
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.