To cite ads in publications use:

  Raphael Pelissier, Francois Goreaud (2015). ads Package for R: A Fast
  Unbiased Implementation of the K-function Family for Studying Spatial
  Point Patterns in Irregular-Shaped Sampling Windows. Journal of
  Statistical Software, 63(6), 1-18. URL
  http://dx.doi.org/10.18637/jss.v063.i06.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {{ads} Package for {R}: A Fast Unbiased Implementation of the $K$-function Family for Studying Spatial Point Patterns in Irregular-Shaped Sampling Windows},
    author = {Rapha{\"e}l P{\'e}lissier and Fran\c{c}ois Goreaud},
    journal = {Journal of Statistical Software},
    year = {2015},
    volume = {63},
    number = {6},
    pages = {1--18},
    url = {http://dx.doi.org/10.18637/jss.v063.i06},
  }