# Please recommend some literature on the systematical theory of the elliptic systems!

Now I'm interested in the theory of elliptic systems, for example, both the linear and nonlinear case, the exsitence and regularity results, and is there a Fredholm alternative result for the linear or nonlinear elliptic system. Further more, may I say that we can parallelly extened the $L^2$-theory of the second-order scalar elliptic equations to the corresponding $\mathbb{L}^2$-theory of the second-order elliptic systems? Any answer and reference will be appreciated!

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The original papers of Agmon, Douglis and Nirenberg are a good place to start. –  Michael Renardy Jun 4 '13 at 13:52
@Michael Renardy: Thank you for your answer! Can you provide some crash guide, lecture notes or good books on elliptic systems for me. Because I have to learn the theory ,and eventually applied them to the system I concerned. –  A.Hoo Jun 4 '13 at 14:09