To cite ppdiag in publications use:

Sun et al., (2021). ppdiag: Diagnostic Tools for Temporal Point Processes. Journal of Open Source Software, 6(61), 3133, https://doi.org/10.21105/joss.03133

Corresponding BibTeX entry:

  @Article{,
    title = {ppdiag: Diagnostic Tools for Temporal Point Processes},
    author = {Sally Sun and Owen G. Ward and Jing Wu and Lihao Xiao and
      Xiaoxi Zhao and Tian Zheng},
    journal = {Journal of Open Source Software},
    year = {2021},
    volume = {6},
    number = {61},
    pages = {3133},
    url = {10.21105/joss.03133},
  }