Introduction to Partial Differential Equations by Don Greenspan (1961 hardcover)

A first course in differential equations with applications by Dennis G. Zill

Nonlinear Partial Differential Equations in Engineering by William F. Ames

Partial Differential Equations by Frederic H. Miller

VTG Partial Differential Equations In Physics by Arnold Sommerfeld - 1953 HC

Partial Differential Equations Fritz John 1982 Fourth Edition Applied

Partial Differential Equations by Lawrence C. Evans

Partial Differential Equations in Physics - Arnold Sommerfeld - 1949 Hardcover