Harvard Business Review, Daniel Goleman, Richard E. Boyatzis, Annie McKee (2015). “HBR's 10 Must Reads on Emotional Intelligence (with featured article "What Makes a Leader?" by Daniel Goleman)(HBR's 10 Must Reads)”, p.3, Harvard Business Review Press
Ken Wilber (2007). “The Integral Vision: A Very Short Introduction to the Revolutionary Integral Approach to Life, God, the Universe, and Everything”, p.38, Shambhala Publications