@article{10027,
  author = {R. Heppner and J. Zorn},
  title = {Near-Threshold Excitation of Metastable Helium by Electron Impact as Studied by the Time-of-Flight Method},
  year = {1974},
  journal = {Physical Review Letters},
  volume = {33},
  pages = {1321-1324},
  month = {Jan-11-1974},
  issn = {0031-9007},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.33.1321},
  doi = {10.1103/PhysRevLett.33.1321},
}