Paper  bibtex   

@article{senn2017superspace,
  title={To superspace and beyond},
  author={Senn, Mark S},
  journal={Acta Crystallographica Section A: Foundations and Advances},
  volume={73},
  number={1},
  pages={1--3},
  year={2017},
  url={https://doi.org/10.1107/S2053273316019902},
  publisher={International Union of Crystallography 5 Abbey Square, Chester, Cheshire CH1~?}
}