Marci Shimoff, Carol Kline, Marianne Williamson (2012). “Love For No Reason: 7 Steps to Creating a Life of Unconditional Love”, p.49, Simon and Schuster
Attributed to Abraham Maslow by Toni Galardi in The LifeQuake Phenomenon: How to Thrive (Not Just Survive) in Times of Personal and Global Upheaval, 2009.