Good Alternatives to Taylor's Volume 3 on PDEs?

[shoehorn]

Does anyone know of a good alternative of Volume 3 of M. E. Taylor's Partial Differential Equations? I'm looking for something at the same level of rigour and which deals with non-linear PDES, particularly non-linear elliptics. The reason I ask is that I've found this particular volume to be the weakest of the three and, well, I've got a need to study elliptic PDEs in a bit more detail.

Thanks in advance.

 

[Kummer]

If you want a lot of theory you can use the books by Evans. But it has a lot of theory.

 

[shoehorn]

Thanks. Yeah, I guess I'm looking for something that's heavy on the theory of PDEs as opposed to the application of them to, say, physics.

Perversely, this is precisely because I'm looking to gain a better understanding of physics. (In particular, I'm interested in estimates for non-linear elliptic formulations of Einstein's equations; I guess this means I'll have to brush up on my weighted Sobolev spaces.)