To cite R2MLwiN in publications use:

Zhang Z, Parker RMA, Charlton CMJ, Leckie G, Browne WJ (2016). “R2MLwiN: A Package to Run MLwiN from within R.” Journal of Statistical Software, 72(10), 1–43. doi:10.18637/jss.v072.i10.

Corresponding BibTeX entry:

    title = {{R2MLwiN}: A Package to Run {MLwiN} from within {R}},
    author = {Zhengzheng Zhang and Richard M. A. Parker and Christopher
      M. J. Charlton and George Leckie and William J. Browne},
    journal = {Journal of Statistical Software},
    year = {2016},
    volume = {72},
    number = {10},
    pages = {1--43},
    doi = {10.18637/jss.v072.i10},