Name	Info	Provider	Link
	subscription/membership/fee required	Ingenta plc	https://www.ingentaconnect.com/openurl?genre=article&issn=0965-0407&volume=7&issue=6&spage=289&aulast=Conway
Cited by Patents in	free resource	The Lens - Patent Citations	https://www.lens.org/lens/search/patent/list?q=citation_id:8527863