TY  - RPRT
TI  - Beyond randomised versus observational studies.
AU  - John Concato
AU  - Ralph I Horwitz
PY  - 2004
DO  - 10.1016/s0140-6736(04)16285-5
UR  - https://pubmed.ncbi.nlm.nih.gov/15158623/
ID  - 15158623
ER  -