@misc{63591,
  author = {E Early and Christopher Cromer and X Xiong and D Dummer and Thomas O'Brian and Albert Parr},
  title = {NIST Reference Densitometer for Visual Diffuse Transmission Density},
  year = {1999},
  number = {43},
  month = {1999-07-26},
  publisher = {Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD},
  url = {https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=841323},
  language = {en},
}