@inproceedings{Brunemann:20132j,
  author = "Brunemann, Johannes",
  title = "{Volume operator}",
  doi = "10.22323/1.140.0016",
  booktitle = "Proceedings of 3rd Quantum Gravity and Quantum Geometry School  {\textemdash} PoS(QGQGS 2011)",
  year = 2013,
  volume = "140",
  pages = "016"
}