I am doing self-study of affine Lie algebras, and while I have all recommended reference material, I find it hard to prepare for the exam.

It was quite easy to study finite-dimensional simple Lie algebras, as there are lots of exercises and solutions, as well as tutorials, available online.

This is the thing that I am missing for the case of affine Lie algebras; so far, I have seen very few exercise solutions, and it seems there are no online tutorials.

**Question:** Is there any book or online reference for exercises with solutions for affine Lie algebras?

In case of a printed book or an unsearchable PDF file, the referenced item can be in English, French, German, Russian, Spanish, or Italian.