To cite the micromap package in publications use:

Payton, Q. and Olsen, A. R. (2014). micromap: Linked Micromap Plots. R package version 1.9. URL: http://www.epa.gov/nheerl/arm/.

Corresponding BibTeX entry:

  @Manual{,
    title = {micromap: Linked Micromap Plots},
    author = {Quinn Payton and Anthony R. Olsen},
    year = {2014},
    note = {R package version 1.9},
    url = {http://www.epa.gov/nheerl/arm/},
  }