Tier 1 extension-Previous earning proof

[Cakebiscuit]

Hello All,
I want to apply for my Tier 1 extension soon and i want to find out what document i need to submit for my self employed(Sole trader) business because i don't intend to use my bank statement.

What other 2 documents would i submit keeping i mind i must not use 2 documents from the same source.

The other additional 2 document i intend to use are
Registration with HMRC with my UTR and
Latetst Annual self assessment tax return


I will be happy if someone can reply me so that i can get myself set.

Thank you.