To cite gRim in publications use:

  Højsgaard, Søren; Edwards, David; Lauritzen, Steffen (2012) Graphical
  Models with R. Springer, New York. ISBN 978-1-4614-2298-3

A BibTeX entry for LaTeX users is

  @Book{,
    title = {Graphical Models with {R}},
    author = {S{\o}ren H{\o}jsgaard and David Edwards and Steffen Lauritzen},
    publisher = {Springer},
    address = {New York},
    year = {2012},
    note = {ISBN 978-1-4614-2298-3},
    doi = {10.1007/978-1-4614-2299-0},
  }