Name	Info	Provider	Link
Cited by Patents in	free resource	The Lens - Patent Citations Database	https://www.lens.org/lens/search/patent/list?q=reference_cited.nlp.ids.pmid:21568370
	subscription/membership/fee required	Silverchair Information Systems	https://pubs.aip.org/asa/jasa/article-lookup/doi/10.1121/1.3565473