@misc{1191821,
  author = {Wilbert F Snyder},
  title = {Circular of the Bureau of Standards no. 439::acoustic performance of 16-millimeter sound 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.439},
  language = {en},
}