TY  - RPRT
TI  - Certification, recertification and added qualifications.
AU  - E S Stauffer
PY  - 1989
DO  - 10.3928/0147-7447-19890501-04
UR  - https://pubmed.ncbi.nlm.nih.gov/2726610/
ID  - 2726610
ER  -