TY  - RPRT
TI  - Choosing the appropriate control.
AU  - P E Morris
AU  - E A Fitzpatrick
PY  - 1999
DO  - 10.1378/chest.115.4.1214-a
UR  - https://pubmed.ncbi.nlm.nih.gov/10208237/
ID  - 10208237
ER  -