TY  - RPRT
TI  - Difficult asthma.
AU  - P J Barnes
AU  - A J Woolcock
PY  - 1998
DO  - 10.1183/09031936.98.12051209
UR  - https://pubmed.ncbi.nlm.nih.gov/9864023/
ID  - 9864023
ER  -