@misc{1191826,
  author = {Robert E Stephens},
  title = {Circular of the Bureau of Standards no. 437::optical and mechanical characteristics of 16-millimeter motion-picture projectors},
  year = {1942},
  month = {1942-01-01 05:01:00},
  publisher = {, National Institute of Standards and Technology, Gaithersburg, MD},
  doi = {https://doi.org/10.6028/NBS.CIRC.437},
  language = {en},
}