To cite fmcmc in publications use:

Vega Yon G, Marjoram P (2019). “fmcmc: A friendly MCMC framework.” The Journal of Open Source Software, 4(39). doi: 10.21105/joss.01427, https://doi.org/10.21105/joss.01427.

And the actual R package:

Vega Yon G, Marjoram P (2021). fmcmc: A friendly MCMC framework. doi: 10.5281/zenodo.3378987, R package version 0.5-0, https://github.com/USCbiostats/fmcmc.

Corresponding BibTeX entries:

  @Article{,
    title = {fmcmc: A friendly MCMC framework},
    author = {George {Vega Yon} and Paul Marjoram},
    journal = {The Journal of Open Source Software},
    year = {2019},
    month = {jul},
    volume = {4},
    number = {39},
    doi = {10.21105/joss.01427},
    url = {https://doi.org/10.21105/joss.01427},
  }
  @Manual{,
    title = {{{fmcmc: A friendly MCMC framework}}},
    author = {George {Vega Yon} and Paul Marjoram},
    year = {2021},
    note = {R package version 0.5-0},
    url = {https://github.com/USCbiostats/fmcmc},
    doi = {10.5281/zenodo.3378987},
  }