TY  - RPRT
TI  - Clinical research designs: quantitative studies.
AU  - Nancy M Heddle
PY  - 2002
DO  - 10.1111/j.1423-0410.2002.tb05312.x
UR  - https://pubmed.ncbi.nlm.nih.gov/12617147/
ID  - 12617147
ER  -