@misc{indiciaeecc937eb39a3,
  title = {Rubidium and cesium frequency standards status and performance on the GPS program},
  author = {Bethke, H. and Ringer, D. and Vanmelle, M.},
  year = {1984},
  url = {https://ntrs.nasa.gov/citations/19850020916},
  note = {Source identifier: 19850020916}
}