All of these materials can be downloaded and used free, without any restrictions. I'll be appreciating if you inform me about using my materials of mention me in your publications if you use my materials. If you can't - it's still Ok.

When I was tutor at "Strategy" Institute for Entrepreneurship I have wrote some books for my students (all they are in Ukrainian):
• C Programming Language. Basics (Мова програмування C. Основи)
• C Standard Library (Мова програмування C. Стандартні функції)

I have also wrote some articles in Ukrainian Wikipedia, you can see them here

If you know Ukrainian you also can read my livejournal