Article 490 of the Civil Code. If the parties enter into a contract in the form of a contract, the contract shall be established when the parties sign, seal or press their fingerprints. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it. A contract shall be concluded in written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.

Enterprises in the purchase and sale of transactions, we should pay attention to the signing of a written contract in content and form that meets the requirements, and ensure that the buyer and the seller affix their official seals to the contract. Moreover, in actual operation, delivery notes, delivery notes, statements and other documents are generally not stamped with the official seal of the company, but only signed by the employees of the receiving party. In the event of a dispute, the delivery note, delivery note and statement of account will be flawed. In order to prevent future disputes, the receiving party denies the validity of its employee's signature. Enterprises can specify the effectiveness of employees' signatures when signing sales contracts.