It is a well-known phenomenon that mathematicians and physicists working on closely-related topics (say in gauge theories, or in general relativity etc.) generally approach the problems from very different angles and often have trouble understanding each other.

In this light, which book(s) do you wish theoretical physicists working on topics intersecting your own research area had read so they could more readily appreciate your work and/or more easily explain their own work to you in terms accessible to you?

To avoid this being opinion-based, please explain what essential concepts or techniques the theoretical physicist would learn from this book(s).