TY  - RPRT
TI  - A pitfall in sampling medical visits.
AU  - D S Shepard
AU  - R Neutra
PY  - 1977
DO  - 10.2105/ajph.67.8.743
UR  - https://pubmed.ncbi.nlm.nih.gov/888991/
ID  - 888991
ER  -