@article{Weiland2009biogas,
  author = {Weiland},
  title = {Biogas production: current state and perspectives},
  journal = {Applied Microbiology and Biotechnology},
  year = {2009},
  doi = {10.1007/s00253-009-2246-7},
  url = {https://doi.org/10.1007/s00253-009-2246-7}
}

@article{Thauer2008methane,
  author = {Thauer and Kaster and Seedorf and others},
  title = {Methanogenic archaea: ecologically relevant differences in energy conservation},
  journal = {Nature Reviews Microbiology},
  year = {2008},
  doi = {10.1038/nrmicro1931},
  url = {https://doi.org/10.1038/nrmicro1931}
}