For her next major work in 1936, "The Ego and the Mechanisms of Defence," a classic monograph on ego psychology and defense mechanisms, Anna Freud drew on her own clinical experience, but relied on her father's writings as the principal and authoritative source of her theoretical insights'. Here her 'cataloguing of regression, repression, reaction formation, isolation, undoing, projection, introjection, turning against the self, reversal and sublimation' helped establish the importance of the ego functions and the concept of defence mechanisms, continuing the greater emphasis on the ego of her father – 'We should like to learn more about the ego' – during his final decades.