Harmonic mappings and minimal immersions : lectures given at the 1st 1984 session of the Centro internationale matematico estivo (C.I.M.E.) held at Montecatini, Italy, June 24-July 3, 1984 / edited by E. Giusti / Enrico Giusti, Italy) Centrointernazionalematematicoestivo.Session(1st:1984:Montecatini