Name	Info	Provider	Link
	subscription/membership/fee required	American Physical Society	https://link.aps.org/abstract/PRL/v109/p203901
Endoscopy	free resource	MedlinePlus Health Information	https://medlineplus.gov/endoscopy.html
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/23215488/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/23215488
Cited by Patents in	free resource	The Lens - Patent Citations	https://www.lens.org/lens/search/patent/list?q=citation_id:23215488