TY  - RPRT
TI  - Proficiency testing programs--promises, progress, and problems. A 40-year prospective.
AU  - R H Laessig
AU  - S S Ehrmeyer
PY  - 1988
UR  - https://pubmed.ncbi.nlm.nih.gov/3355326/
ID  - 3355326
ER  -