To cite truncSP in publications use:

Maria Karlsson, Anita Lindmark (2014). truncSP: An R Package for Estimation of Semi-Parametric Truncated Linear Regression Models. Journal of Statistical Software, 57(14), 1-19. URL http://www.jstatsoft.org/v57/i14/.

Corresponding BibTeX entry:

  @Article{,
    title = {{truncSP}: An {R} Package for Estimation of
      Semi-Parametric Truncated Linear Regression Models},
    author = {Maria Karlsson and Anita Lindmark},
    journal = {Journal of Statistical Software},
    year = {2014},
    volume = {57},
    number = {14},
    pages = {1--19},
    url = {http://www.jstatsoft.org/v57/i14/},
  }