TY  - RPRT
TI  - Research study designs: non-experimental.
AU  - Cheryl Bagley Thompson
AU  - Edward A Panacek
DO  - 10.1016/j.amj.2006.10.003
UR  - https://pubmed.ncbi.nlm.nih.gov/17210489/
ID  - 17210489
ER  -