Reference:
  Author: Jason P. Fine and Robert J. Gray
  Title: "A proportional hazards model for the subdistribution of a competing risk"
  Journal: J Am Stat Assoc
  Year: 1999
  Volume: 94
  Number: 446
  Pages: 496-509
  DOI: 10.2307/2670170
  URL: http://www.tandfonline.com/doi/abs/10.1080/01621459.1999.10474144
Archive: CRAN
