TY  - RPRT
TI  - Difficult asthma.
AU  - P J Barnes
AU  - K F Chung
PY  - 1989
DO  - 10.1136/bmj.299.6701.695
UR  - https://pubmed.ncbi.nlm.nih.gov/2508876/
ID  - 2508876
ER  -