1) Various proofing documents indicating the place of employment, place of both and place and date of residence of overseas Chinese, including ID cards, residence cards, employment permit and business license as well as proofing documents issued by consulate general, overseas Chinese missions and notarizations institutions 2) Date of leaving the country as has been registered on the residential book of Hukou. 3) Owner identity registered on the file and documents during land reform, socialist reform and trustee period. 4) Autobiography written by relatives in China before 1966, information on the registration form of workers and other relevant documents provided by various institutions. 5) Information collected by government institutions responsible for overseas Chinese at various levels. 6) Registration or proof of overseas remittance that indicate year and date. 7) Overseas letters from that time.