@misc{indiciae5cbe7ff355c7,
  title = {Variation and progress.},
  author = {J A Nevin},
  year = {1987},
  doi = {10.1901/jeab.1987.48-489},
  url = {https://pubmed.ncbi.nlm.nih.gov/16812524/},
  note = {Source identifier: 16812524}
}