APA   Click to copy
Graven, A. J., & Hubbard, J. H. (2021). An Elementary Proof of Poincaré’s Last Geometric Theorem. PUCP Pro Mathematica, 31(62), 61–93.

Chicago/Turabian   Click to copy
Graven, Andrew J., and John H. Hubbard. “An Elementary Proof of Poincaré’s Last Geometric Theorem.” PUCP Pro Mathematica 31, no. 62 (2021): 61–93.

MLA   Click to copy
Graven, Andrew J., and John H. Hubbard. “An Elementary Proof of Poincaré’s Last Geometric Theorem.” PUCP Pro Mathematica, vol. 31, no. 62, 2021, pp. 61–93.

@article{andrew2021a,
  title = {An Elementary Proof of Poincaré’s Last Geometric Theorem},
  year = {2021},
  issue = {62},
  journal = {PUCP Pro Mathematica},
  pages = {61-93},
  volume = {31},
  author = {Graven, Andrew J. and Hubbard, John H.}
}