TY  - RPRT
TI  - Modifications to expiratory valves.
AU  - B E Welsh
PY  - 1990
DO  - 10.1111/j.1365-2044.1990.tb14719.x
UR  - https://pubmed.ncbi.nlm.nih.gov/2334049/
ID  - 2334049
ER  -