@article{allan2015the,
  title = {The water–food–energy nexus: an introduction to nexus concepts and some conceptual and operational problems}
  author = {Allan, Tony; Keulertz, Martin; Woertz, Eckart},
  journal = {Factor X: Challenges, Implementation Strategies and Examples for a Sustainable Use of Natural Resources},
  url = {https://doi.org/10.1080/07900627.2015.1029118},
  doi = {10.1080/07900627.2015.1029118},
  year = {2015}
}