Name	Info	Provider	Link
Full text from	free resource	CORE	https://core.ac.uk/reader/77010757?utm_source=linkout
	free resource	Spiral, Imperial College Digital Repository	http://hdl.handle.net/10044/1/31692
	free resource	Via Medica Medical Publishers	http://czasopisma.viamedica.pl/imh/article/view/41505