To cite cosa in publications use:

Bulus M, Dong N (2019). cosa: Bound Constrained Optimal Sample Allocation. R package version 2.0.0, https://CRAN.R-project.org/package=cosa.

Corresponding BibTeX entry:

  @Manual{,
    title = {{cosa}: Bound Constrained Optimal Sample Allocation},
    author = {Metin Bulus and Nianbo Dong},
    note = {R package version 2.0.0},
    year = {2019},
    url = {https://CRAN.R-project.org/package=cosa},
  }