There are already several questions on *MathOverflow* that inquire about the many diverse relationships between PDE and several other 'areas' of mathematics (e.g., algebraic and differential geometry and topology, number theory, harmonic analysis, probability theory, dynamical systems, etc.); however, most of the answers give only a few particular examples.

The aim of this question is to collect a [big-list] of **references** (i.e., *broad surveys* or *monographs*) that specifically focus on the role played by PDE in various other areas of mathematics, or on methods "stemming from other topics" that are used in the analysis of PDE.