To cite the micromap package in publications use:

Payton Q, Olsen T, Weber M, McManus M, Kincaid T, Beck M (2015). “micromap: A Package for Linked Micromaps.” Journal of Statistical Software, 63(2), 1–16. doi:10.18637/jss.v063.i02.

Corresponding BibTeX entry:

    title = {{micromap}: A Package for Linked Micromaps},
    author = {Quinn Payton and Tony Olsen and Marc Weber and Michael
      McManus and Tom Kincaid and Marcus W. Beck},
    journal = {Journal of Statistical Software},
    year = {2015},
    volume = {63},
    number = {2},
    pages = {1--16},
    doi = {10.18637/jss.v063.i02},