Name	Info	Provider	Link
	subscription/membership/fee required	Ingenta plc	https://www.ingentaconnect.com/openurl?genre=article&issn=&volume=7&issue=2&spage=135&aulast=Valverde
	subscription/membership/fee required	Bentham Science Publishers Ltd.	https://www.eurekaselect.com/87595/article
Full text from	free resource	CORE	https://core.ac.uk/reader/34498268?utm_source=linkout
Full text from	free resource	Diposit Digital de la Universitat de Barcelona	http://hdl.handle.net/2445/164347