To cite the 'Ryacas' package in publications use:

Andersen M, Højsgaard S (2019). “Ryacas: A computer algebra system in R.” Journal of Open Source Software, 4(42). https://doi.org/10.21105/joss.01763.

Corresponding BibTeX entry:

  @Article{,
    title = {{Ryacas: A computer algebra system in R}},
    author = {Mikkel Meyer Andersen and Søren Højsgaard},
    journal = {Journal of Open Source Software},
    year = {2019},
    volume = {4},
    number = {42},
    url = {https://doi.org/10.21105/joss.01763},
  }