How do I prove that I am the author of Envato?



Hello. I had difficulties in filling tax return in my country. I get the money to my bank account via Skrill system. The difficulty lies in the fact that I have to prove that the money is coming from abroad. I live in Russia. I have a question. Can I receive an electronic confirmation from Envato, what I am the author? How can I prove that the money on my bank account was from earnings on Envato? (Skrill delivers only CSV help and it is not proof.)