To cite mritc in publications use:

  Dai Feng, Luke Tierney (2011). mritc: A Package for MRI Tissue
  Classification. Journal of Statistical Software, 44(7), 1-20. URL
  https://www.jstatsoft.org/v44/i07/.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {{mritc}: A Package for {MRI} Tissue Classification},
    author = {Dai Feng and Luke Tierney},
    journal = {Journal of Statistical Software},
    year = {2011},
    volume = {44},
    number = {7},
    pages = {1--20},
    url = {https://www.jstatsoft.org/v44/i07/},
  }