To cite survsim in publications use:

MoriƱa D, Navarro A (2014). “The R Package survsim for the Simulation of Simple and Complex Survival Data.” Journal of Statistical Software, 59(2), 1–20. doi: 10.18637/jss.v059.i02.

Corresponding BibTeX entry:

  @Article{,
    title = {The {R} Package {survsim} for the Simulation of Simple and
      Complex Survival Data},
    author = {David Mori{\~n}a and Albert Navarro},
    journal = {Journal of Statistical Software},
    year = {2014},
    volume = {59},
    number = {2},
    pages = {1--20},
    doi = {10.18637/jss.v059.i02},
  }