1. Fleming TR, Harrington DP (1991). Counting Processes and Survival Analysis. New York: J. Wiley Sons.
2. Andersen PK, Borgan O, Gill RD, Keiding N (1993). Statistical Models Based on Counting Processes. New York: Springer-Verlag.
3. Kay R (1984) Goodness-of-fit methods for the proportional hazards model: a review. Rev Epidemiol Santé Publ 32:185–198.
4. Lin DY, Wei LJ (1991). Goodness-of-fit tests for the general Cox regression model. Stat Sinica 1:1–17.
5. Cox DR (1972). Regression models and life-tables (with discussion). J R Stat Soc B 34: 187–220.