@misc{1173606,
  author = {PR Heyl},
  title = {Letter Circular 188::sound proof partitions},
  year = {1925},
  month = {1925-01-01 05:01:00},
  publisher = {, National Institute of Standards and Technology, Gaithersburg, MD},
  doi = {https://doi.org/10.6028/NBS.LCIRC.188},
  language = {en},
}