@misc{indiciae25a1f01045ae,
  title = {An expanding genetic code.},
  author = {T Ashton Cropp and Peter G Schultz},
  year = {2004},
  doi = {10.1016/j.tig.2004.09.013},
  url = {https://pubmed.ncbi.nlm.nih.gov/15522458/},
  note = {Source identifier: 15522458}
}