To cite NAM in publications use:

  Xavier A, et al. (2019). NAM: association studies in multiple
  populations. Bioinformatics 31(23):3862-3864.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {NAM: association studies in multiple populations},
    author = {Alencar Xavier and William Muir and Shizhong Xu and Katy Rainey},
    journal = {Bioinformatics},
    volume = {31},
    number = {23},
    year = {2015},
    pages = {3862-3864},
    doi = {10.1093/bioinformatics/btv448},
  }