1. Ayerbe-Chaux, Reinaldo, “El Conde Lucanor”. Materia tradicional y originalidad creadora, Madrid, Porrúa-Turanzas, 1975.
2. Blackmore, Susan J., Beyond the body. An investigation of out-of-the-body experiences, Chicago, Academy Chicago Publishers, 1991.
3. Collins, Roger, Julian of Toledo and the education of kings in late seventh-century Spain, in: Collins, Roger (ed.), Law, culture and regionalism in early medieval Spain, London/New York, Routledge, 1992, 1‒22.
4. Collins, Roger, Early Medieval Spain. Unity in diversity, 400‒1000, New York, St. Martin’s Press, 21995, 77‒78.
5. Collins, Roger, Visigothic Spain, 409‒711, Oxford, Blackwell, 2004.