TY  - RPRT
TI  - Observational studies for intervention assessment.
AU  - A Jahn
AU  - O Razum
PY  - 2001
DO  - 10.1016/s0140-6736(00)05218-1
UR  - https://pubmed.ncbi.nlm.nih.gov/11448009/
ID  - 11448009
ER  -