1. Jim Collins on the Hedgehog Concept

https://www.jimcollins.com/media_topics/PersonalHedgehogConcept.html
https://www.jimcollins.com/concepts/the-hedgehog-concept.html

2. Daniel Goleman, Emotional Intelligence (Συναισθηματική Νοημοσύνη — το βιβλίο είναι διαθέσιμο και στα ελληνικά)

3. The Big Five Personality Model

https://en.wikipedia.org/wiki/Big_Five_personality_traits

4. The Big Five Personality Model

https://www.verywellmind.com/the-big-five-personality-dimensions-2795422