Schrödinger Operators, Como 1984: Lectures given at the 2nd 1984 Session of the Centro Internationale Matematico Estivo (C.I.M.E.) held at Como, Italy, Aug.26- Sept.4, 1984

Transition to Chaos in Classical and Quantum Mechanics: Lectures given at the 3rd Session of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Montecatini Terme, Italy, July 6 - 13, 1991