@article{8053,
  author = {S. Chu and Allen Mills and John Hall},
  title = {Measurement of the Positronium 1 Triplet S1 to 2 Triplet S1 Interval by Doppler-Free Two-Photon Spectroscopy},
  year = {1984},
  journal = {Physical Review Letters},
  volume = {52},
  pages = {1689-1692},
  month = {Jan-05-1984},
  issn = {0031-9007},
  doi = {10.1103/PhysRevLett.52.1689},
}