TY  - RPRT
TI  - A practical approach to designing and performing a focused study.
AU  - M M Jackson
PY  - 1997
DO  - 10.1016/s0196-6553(97)90074-2
UR  - https://pubmed.ncbi.nlm.nih.gov/9437489/
ID  - 9437489
ER  -