When both parties sign a contract, it is valid as long as it is the true intention of the parties, even if only the surname is signed. Article 490 of the General Principles of the Civil Law When concluding a contract, if the parties conclude the contract in the form of a contract, the contract shall be established when the parties sign, seal or fingerprint it. 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.