TY  - RPRT
TI  - Research design.
AU  - M E Megel
AU  - J A Heermann
PY  - 1993
DO  - 10.1097/00006527-199301340-00010
UR  - https://pubmed.ncbi.nlm.nih.gov/8121952/
ID  - 8121952
ER  -