Lectures given at a Summer School of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Varenna (Como), Italy, September 9-17, 1968

Lectures given at a Summer School of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Stresa (Varese), Italy, July 2-10, 1969

Lectures given at a Summer School of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Bressanone (Bolzano), Italy, June 3-12, 1973

Lectures given at a Summer School of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Bressanone (Bolzano), Italy, June 21-27, 1976

Lectures given at a Summer School of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Varenna (Como), Italy, June 16-25, 1974

Lectures given at a Summer School of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Varenna (Como), Italy, August 20-29, 1970

Lectures given at a Summer School of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Bressanone (Bolzano), Italy, June 8-17, 1980

Lectures given at a Summer School of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Bressanone (Bolzano), Italy, June 10-18, 1966

Lectures given at a Summer School of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Montecatini Terme (Pistoia), Italy, June 25 - July 4, 1970

Lectures given at a Summer School of the Centro Internazionale Matematico Estivo (C.I.M.E.) held in Bressanone (Bolzano), Italy, June 4-13, 1972