@misc{indiciae6ceb76d3cee0,
  title = {Audio amplification in pyelolithotomy and nephrolithotomy.},
  author = {R Zufall and W Pomerantz},
  year = {1969},
  doi = {10.1016/s0022-5347(17)62198-0},
  url = {https://pubmed.ncbi.nlm.nih.gov/5347760/},
  note = {Source identifier: 5347760}
}