Source doents include all of the following except?

I would think a source doent is one that comes from the source so that you can rely on it to have issued or committed to it. Everything there except a ledger are issued by the source and could conceivably be held aqainst the issuer ("source) without any doubt about fraud. The ledger however, is kept by a third party, perhaps the debtor or creditor, and is a kind of written hearsay, about which the author could easily fraudulently create false information. So I would think the ledger is the non source doent.