If you use PFFRGSolver.jl, please acknowledge the package accordingly and cite our preprint
D. Kiese, T.Müller, Y. Iqbal, R. Thomale and S. Trebst, "Multiloop functional renormalization group approach to quantum spin systems", arXiv:2011.01269 (2020)

A suitable bibtex entry is:
@misc{kiese2020multiloop,
      title={Multiloop functional renormalization group approach to quantum spin systems},
      author={Dominik Kiese and Tobias M\"uller and Yasir Iqbal and Ronny Thomale and Simon Trebst},
      year={2020},
      eprint={2011.01269},
      archivePrefix={arXiv},
      primaryClass={cond-mat.str-el}
}
