Identify the items from the following list that are likely to serve as source documents. (You may select more than one answer. Single click the box with the question mark to produce a check mark for a correct answer and double click the box with the question mark to empty the box for a wrong answer.)
1. Check
2. Statement of cash flows
3. Ledger
4. Prepaid insurance account
5. Invoice from supplier
6. Income statement
7. Company revenue account
8. Bank statement
9. Purchase order