These lectures represent a pioneering investigation by the author. Basing his research on prior studies by Riemann, Kirchhoff, and Volterra, he extends and improves Volterra's work, applying its theories relating to spherical and cylindrical waves to all normal hyperbolic equations. Topics include the general properties of Cauchy's problem, the fundamental formula and the elementary solution, more. 1923 edition. Unabridged reprint of the 1923 edition.
Here's a sample of other books in this Dover category
Boundary and Eigenvalue Problems in Mathematical Physics by Hans Sagan Well-known text uses a few basic concepts to solve such problems as the vibrating string, vibrating membrane, and heat conduction. Problems and solutions. 31 illustrations.
Lectures on Partial Differential Equations by I. G. Petrovsky Graduate-level exposition by noted Russian mathematician offers rigorous, readable coverage of classification of equations, hyperbolic equations, elliptic equations, and parabolic equations. Translated from the Russian by A. Shenitzer. 1954 edition.
