@techreport{Steinberg1991,
author = {Steinberg, D. },
title= {Competing risk multi-spell survival analysis: the CTM procedure},
year = {1991},
URL = {http://www.sascommunity.org/sugi/SUGI91/Sugi-91-267%20Steinberg.pdf
%[21 March 2014},
publisher = {SAS Institute Inc. Proceedings of the Sixteenth Annual SAS Users Group International Conference, Sugi-91-267, SAS Institute, Cary, NC},
}