@book{Andersen1993,
author = {Andersen, P.K. and Borgan, O. and Gill, R.D. and Keiding, N.},
title= {Statistical models based on counting processes},
year = {1993},
doi = {10.1007/978-1-4612-4348-9},
address = {New York},
publisher = {Springer},
}