Integral operators in the theory of linear partial differential equations. / Bergman, Stefan. Bergman, Stefan, 1898-1977. Differential equations, Partial. Integrals. QA374 .B38 517.383 BEI Includes index Bibliography: p. 132-143 Berlin, Springer, 1961. 1961. 1961 Text x, 145 p. : eng Ergebnisse der Mathematik und ihrer Grenzgebiete, n.F., Heft 23