Differential Equation: Theory of Ordinary Differential Equations, Coddington and Levinson| Ordinary Differintial Equations Miller & Michel| Partial Differential Equations, Fritz John| Partial Differential Equations, Evans

Applied Math: Applied Analysis, Hunter

Functional Analysis: Functional Analysis, Peter D. Lax

Numerical Analysis: Numerical Analysis, Hammerlin

Finite Element: Mathematical Theory of Finite Element Methods, Brenner