PART I
Section 2: First-order Equations
Section 4: Second-order Equations
Section 5: Wave Equation on the Real Line
Section 6: Wave Equation on an Interval
Section 7: Wave Equation in Higher Dimensions
Section 8: Hyperbolic Systems of First-Order Equations
PART II
Section 5 Addendum: Physical Interpretation of Single and Double-Layer Potentials
Section 6: Eigenvalues of the Laplacian
Section 6 Addendum: Comments on Rayleigh-Ritz Approximation and Minimax Principle