@misc{indiciae5a4646faa881,
  title = {Optically excited states in positronium},
  author = {Howell, R. H. and Ziock, Klaus P. and Magnotta, F. and Dermer, Charles D. and Failor, R. A. and Jones, K. M.},
  year = {1990},
  url = {https://ntrs.nasa.gov/citations/19900009669},
  note = {Source identifier: 19900009669}
}