1. Leopardi, G. La Ginestra (1836). Available with parallel italian and english texts on http://www.tclt.org.uk/leopardi/Canti_2011.pdf, page 212
2. Csikszentmihalyi M, Nakamura J, Csikszentmihalyi M (2014) The concept of flow. In: Flow and the foundations of positive psychology: the collected works of Mihaly Csikszentmihalyi.
3. Peterson JB (2002) Maps of meaning: the architecture of belief. Routledge
4. Zagrebelsky G (2015) Liberi servi. Il Grande Inquisitore e l’enigma del potere, Torino: Einaudi
5. Freud S (1929) Civilization and its discontents