@misc{indiciae20e69f32a318,
  title = {Chemical evolution of dense clouds},
  author = {Chapelle, E. W. and Donn, B. D. and Payne, W. A., Jr. and Stief, L. J.},
  year = {1973},
  url = {https://ntrs.nasa.gov/citations/19740042537},
  note = {Source identifier: 19740042537}
}