To cite the 'MCI' package in publications use:

  Wieland, T. (2017). Market Area Analysis for Retail and Service
  Locations with MCI. The R Journal, 9(1), 298-323. URL
  https://journal.r-project.org/archive/2017/RJ-2017-020/RJ-2017-020.pdf.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {{M}arket {A}rea {A}nalysis for {R}etail and {S}ervice {L}ocations with {MCI}},
    author = {Thomas Wieland},
    year = {2017},
    journal = {The R Journal},
    volume = {9},
    number = {1},
    pages = {298--323},
    url = {https://journal.r-project.org/archive/2017/RJ-2017-020/RJ-2017-020.pdf},
  }