@misc{indiciae95d805efd958,
  title = {Direct observation of hyperfine structure in pi mesic X rays.},
  author = {Carrigan, R. A., Jr. and Sapp, W. W. and Shuler, W. B. and Siegel, R. T. and Welsh, R. E.},
  year = {1967},
  url = {https://ntrs.nasa.gov/citations/19680032302},
  note = {Source identifier: 19680032302}
}