The foreign affairs documents, financial loan slips and reimbursement vouchers handled by the workers can directly prove the existence of labor relations between the two parties.
In the absence of a labor contract, social insurance payment records can be used as proof of the existence of labor relations. Laborers can also collect and provide other materials: work permit with company name, work clothes, documents with company seal that can be embodied as employees of the company, salary payment records, witness testimony, audio and video recordings, etc.