To cite MWASTools:

  Rodriguez-Martinez A, Ayala R, Posma JM, Neves AL, Anwar M, Pettreto
  E, Emanueli C, Gauguier D, Nicholson JK, Dumas ME. 2017. MWASTools:
  an R/Bioconductor package for metabolome-wide association studies.
  Bioinformatics

A BibTeX entry for LaTeX users is

  @Article{,
    author = {Andrea Rodriguez-Martinez and Joram M Posma and Rafael Ayala and Ana L Neves and Maryam Anwar and Enrico Petretto and Constanza Emanueli and Dominique Gauguier and Jeremy K Nicholson and Marc-Emmanuel Dumas},
    title = {MWASTools: an R/Bioconductor package for metabolome-wide association studies},
    journal = {Bioinformatics},
    year = {2017},
    doi = {https://doi.org/10.1093/bioinformatics/btx477},
  }