To cite package ‘RTriangle’ in publications use:

  Shewchuk J (1996). “Triangle: Engineering a 2D quality mesh generator
  and Delaunay triangulator.” In Lin M, Manocha D (eds.), _Applied
  Computational Geometry: Towards Geometric Engineering_, volume 1148
  series Lecture Notes in Computer Science, 203-222. Springer-Verlag.
  From the First ACM Workshop on Applied Computational Geometry.

A BibTeX entry for LaTeX users is

  @InCollection{,
    title = {Triangle: {Engineering} a {2D} quality mesh
                  generator and {Delaunay} triangulator},
    author = {Jonathan Richard Shewchuk},
    year = {1996},
    month = {may},
    booktitle = {Applied Computational Geometry: Towards Geometric
                  Engineering},
    editor = {Ming C. Lin and Dinesh Manocha},
    series = {Lecture Notes in Computer Science},
    volume = {1148},
    publisher = {Springer-Verlag},
    pages = {203-222},
    note = {From the First ACM Workshop on Applied Computational
                  Geometry},
  }