To cite alpaca in publications use:

Stammann, Amrei (2018). Fast and Feasible Estimation of Generalized Linear Models with High-Dimensional k-way Fixed Effects. ArXiv e-prints. URL https://arxiv.org/pdf/1707.01815.pdf.

Corresponding BibTeX entry:

  @Article{,
    title = {Fast and Feasible Estimation of Generalized Linear Models
      with High-Dimensional k-way Fixed Effects},
    author = {Amrei Stammann},
    journal = {ArXiv e-prints},
    year = {2018},
    url = {https://arxiv.org/pdf/1707.01815.pdf},
  }