TY  - RPRT
TI  - A modified expiratory valve for teaching.
AU  - A J Sansome
AU  - R Bacon
PY  - 1989
DO  - 10.1111/j.1365-2044.1989.tb11345.x
UR  - https://pubmed.ncbi.nlm.nih.gov/2742104/
ID  - 2742104
ER  -