This well-known advanced undergraduate- and graduate-level text uses a few basic concepts to solve and develop complete answers to linear homogeneous partial differential equations such as the problems of the vibrating string, the vibrating membrane, and heat conduction. With problems and solutions. 31 illustrations.
Here's a sample of other books in this Dover category
Lectures on Cauchy's Problem in Linear Partial Differential Equations by Jacques Hadamard Basing his research on prior studies by Riemann, Kirchhoff, and Volterra, the author extends and improves Volterra's work, applying its theories relating to spherical and cylindrical waves to all normal hyperbolic equations. 1923 edition.
Nonstandard Methods in Stochastic Analysis and Mathematical Physics by Sergio Albeverio, Jens Erik Fenstad, Raphael Høegh-Krohn, Tom Lindstrøm Two-part treatment begins with a self-contained introduction to the subject, followed by applications to stochastic analysis and mathematical physics. "A welcome addition." — Bulletin of the American Mathematical Society. 1986 edition.
Mathematics for the Physical Sciences by Laurent Schwartz Concise treatment of mathematical entities employs examples from the physical sciences. Topics include distribution theory, Fourier series, Laplace transforms, wave and heat conduction equations, and gamma and Bessel functions. 1966 edition.
Fundamentals of Mathematical Physics by Edgar A. Kraut Indispensable for students of modern physics, this text provides the necessary background in mathematics to study the concepts of electromagnetic theory and quantum mechanics. 1967 edition.