To cite package ‘einsum’ in publications use:

  Ahlmann-Eltze C (2024). _einsum: Einstein Summation_. R package
  version 0.1.2, <https://github.com/const-ae/einsum>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {einsum: Einstein Summation},
    author = {Constantin Ahlmann-Eltze},
    year = {2024},
    note = {R package version 0.1.2},
    url = {https://github.com/const-ae/einsum},
  }