Name	Info	Provider	Link
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/31063274/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/31063274
	free resource	COPD Foundation	https://doi.org/10.15326/jcopdf.6.2.2018.0151