Lectures on Riemann surfaces : proceedings of the College on Riemann Surfaces, International Centre for Theoretical Physics, Trieste, Italy, 9 Nov.-18 Dec., 1987 / by College on Riemann Surfaces (1st : 1987 : International Centre for Theoretical Physics), Cornalba, M. (Maurizio), Gomez-Mont, X. (Xavier), 1951-, Verjovsky, A., International Centre for Theoretical Physics