To cite package ‘metaCCA’ in publications use:

  Cichonska et al. (2016) metaCCA: Summary statistics-based
  multivariate meta-analysis of genome-wide association studies using
  canonical correlation analysis. Bioinformatics, 32(13):1981-1989.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {metaCCA: Summary statistics-based multivariate meta-analysis
         of genome-wide association studies using canonical correlation analysis},
    author = {{Anna Cichonska} and {Juho Rousu} and {Pekka Marttinen} and {Antti J Kangas} and {Pasi Soininen} and {Terho Lehtimaki} and {Olli T Raitakari} and {Marjo-Riitta Jarvelin} and {Veikko Salomaa} and {Mika Ala-Korpela} and {Samuli Ripatti} and {Matti Pirinen}},
    year = {2016},
    journal = {Bioinformatics},
    volume = {32},
    pages = {1981-1989},
    doi = {10.1093/bioinformatics/btw052},
    url = {https://doi.org/10.1093/bioinformatics/btw052},
  }