Brogan AJ, Stidham S. A note on separation in mean-lower-partial-moment portfolio optimization with fixed and moving targets. IIE Trans. 2005 Jan 1;37(10):901-6.
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.