Sub plan on theorems about sums of squares

[Liu]

I am at the point of reading the last chapter of the book “complex
analysis” by Elias Stein and Rami Shakarchi. This is about a
application of Theta function, to prove a well known theorem about the
sums of squares in number theorem. After this chapter, I will do some
exercises of this book. Always feel good to finish something, although
it is actually another start point.