To cite package 'marked' in publications use:

  Laake, J.L., D.S. Johnson, and P.B. Conn. 2013. marked: An R package
  for maximum-likelihood and MCMC analysis of capture-recapture data.
  Methods Ecol. Evol. 4:885-890.

A BibTeX entry for LaTeX users is

  @Article{,
    author = {J.L. Laake and D.S. Johnson and P.B. Conn},
    year = {2013},
    title = {marked: An R package for maximum-likelihood and MCMC analysis of capture-recapture data.},
    journal = {Methods in Ecology and Evolution},
  }