Maldonado, Enrique F., Francisco J. Fernandez, M. Victoria Trianes, Keith Wesnes, Orlando Petrini, Andrea Zangara, Alfredo Enguix, and Lara Ambrosetti. 2008. “Cognitive performance and morning levels of salivary cortisol and α-Amylase in children reporting high vs. low daily stress perception”. The Spanish Journal of Psychology 11, nº 1:: 3-15. https://revistas.ucm.es/index.php/SJOP/article/view/SJOP0808120003A