Name	Info	Provider	Link
	subscription/membership/fee required	HighWire	https://www.bmj.com/lookup/pmidlookup?view=long&pmid=22550349
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=22550349.ui
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22550349/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/22550349
Full text from	free resource	White Rose Research Online	https://eprints.whiterose.ac.uk/113800/