TY  - RPRT
TI  - Problems in doing nursing research. Control by constancy: will it work in clinical research?
AU  - A S Hinshaw
PY  - 1979
DO  - 10.1177/019394597900100224
UR  - https://pubmed.ncbi.nlm.nih.gov/258019/
ID  - 258019
ER  -