@misc{1190911,
  author = {A H Morgan},
  title = {Preliminary instructions for obtaining and reducing manual ionospheric records:},
  year = {1947},
  month = {1947-01-01 05:01:00},
  publisher = {, National Institute of Standards and Technology, Gaithersburg, MD},
  doi = {https://doi.org/10.6028/NBS.CRPL.7-1},
  language = {en},
}