Any document from which the source of receipt of these funds is clear (where the funds came from) is suitable as a source of confirmation of funds; your full name must be indicated in the document. For example:
bank account statement for a period of at least 3 months;
salary certificate for the last 3 months;
dividend payment decisions and bank account statements (if you receive dividends);
deposit agreement together with account statement;
loan agreement, other agreement confirming the source of funds;
screenshots and extracts from trading platforms (if you are involved in trading);
screenshots and extracts from mining pools (if you are engaged in mining);
an agreement for the sale of expensive property along with an account statement, if such a sale was carried out in during the last three years;
any other documents confirming your source of funds.