@misc{indiciaede8853951482,
  title = {Positronium formation in positron-helium scattering.},
  author = {Fels, M. F. and Mittleman, M. H.},
  year = {1969},
  url = {https://ntrs.nasa.gov/citations/19690065826},
  note = {Source identifier: 19690065826}
}