@misc{indiciae0143f6cb8c7b,
  title = {Bleaching discoloured root-filled teeth.},
  author = {R A Howell},
  year = {1980},
  doi = {10.1038/sj.bdj.4804406},
  url = {https://pubmed.ncbi.nlm.nih.gov/6928778/},
  note = {Source identifier: 6928778}
}