Which document establishes an initial record of the receipt of the inventory? petty cash voucher purchase order vendor's invoice receiving report?

The answer is receiving report.

Explanation:

Receiving report shows that the product ordered has been received by the purchaser from the vendor. Vendor's invoice usually come after the receiving report and generally would be sent following that document, either separately or together. Purchase order would come before receiving report as an initial agreement to purchase a number of products from a vendor. Petty case vouchers are not related to external transactions with a vendor, but are instead used for internal-related business transactions.