TY  - RPRT
TI  - Identifiability, stratification and minimum variance estimation of causal effects.
AU  - Xingwei Tong
AU  - Zhongguo Zheng
AU  - Zhi Geng
PY  - 2005
DO  - 10.1002/sim.2153
UR  - https://pubmed.ncbi.nlm.nih.gov/16149123/
ID  - 16149123
ER  -