References on PDEs and Functional Analysis

• Salsa S. - Partial Differential Equations in Action
• Quarteroni, A.; Sacco, A. Saleri, F. — Numerical Mathematics.pdf
• Clarke, F. H. - Functional Analysis, Calculus of Variations and Optimal Control
• Ewing, G. M. — Calculus of Variations with Applications
• Farenick, D. — Fundamentals of Functional Analysis.pdf
• Lebedev, L. P. — The Calculus of Variations and Functional Analysis With Optimal Control and Applications in Mechanics.pdf