# References for the nonlinear reaction-diffusion equation using Finite Element Methods

I want to study how to solve the following PDE

$$\begin{cases} -\nabla \cdot(\ k(x,y) \ \nabla u \ ) + \beta(x,y)\ u^2 = f(x,y), \ (x,y) \in \Omega \subset \mathbb{R^2} \\ \hspace{0.5cm} u = g_{D} \ \ on \ \ \partial{\Omega}_{D} \\ \hspace{0.2cm} \frac{\partial{u}}{ \partial n } = g_{N} \ \ on \ \ \partial{\Omega}_{N} \end{cases}$$

I know how to solve the linear version of this PDE with the finite element method.

This is my first time with a nonlinear PDE, so I have to start with theory (from the most basic to the advanced), and then read about implementation details.