title: Proficiency Analytical Testing Program report (March 1996).
authors.affiliation: Centers for Disease Control and Prevention, Division of Physical Sciences and Engineering, Cincinnati, OH, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Esche
authors.forename: J H
authors.initials: JH
authors.lastname: Groff
mesh_terms: D007753:Laboratories / Q000592:standards*; D016272:Occupational Health; D011786:Quality Control; D012015:Reference Standards