National Institute of Standards and Technology
National Institute of Standards and Technology (<a rel="nofollow" class="external free" href="http://nistdigitalarchives.contentdm.oclc.org/cdm/singleitem/collection/p16009coll21/id/5/rec/12">http://nistdigitalarchives.contentdm.oclc.org/cdm/singleitem/collection/p16009coll21/id/5/rec/12</a>)