Volterra equations proceedings of the Helsinki Symposium on Integral Equations, Otaniemi, Finland, August 11-14, 1978 / edited by Stig-Olof Londen and Olof J. Staffans. - Londen, Stig-Olof; Staffans, Olof J., 1947- (Lecture notes in mathematics (Springer-Verlag), 1979)