General merchandise invoice. Because the purchase of printed matter sales does not involve any other special invoice issuing threshold, the purchase of printed matter sales issues ordinary commodity invoices. Invoice refers to the business vouchers issued and collected by all units and individuals in buying and selling goods, providing or receiving services and engaging in other business activities. It is the original basis of accounting, and it is also an important basis for law enforcement inspection by audit institutions and tax authorities. Receipt is the proof of receipt and payment, and invoice can only prove that the business has happened, but can't prove whether the money has been received or paid.