To cite R/qtlbook in publications use:

Broman and Sen (2009) A Guide to QTL Mapping with R/qtl. Springer, New York

Corresponding BibTeX entry:

  @Book{,
    title = {A Guide to {QTL} Mapping with {R}/qtl},
    author = {Karl W. Broman and Saunak Sen},
    publisher = {Springer},
    year = {2009},
    address = {New York},
  }