Who among the following is not associated with theories of motivation ?

Abraham Maslow (Need Hierarchy Theory), Chris Argyris (Immaturity-Maturity Theory), and Frederick Herzberg (Two-Factor Motivation-Hygiene Theory) are renowned behavioural theorists of work motivation. 'Peter F. Drucker' is renowned for Management by Objectives (MBO), corporate strategy, and general management rather than psychological theories of motivation.