22 CFR §51.43

1. (a)General. A person born outside the United States must submit documentary evidence that he or she meets all the statutory requirements for acquisition of U.S. citizenship or non-citizen nationality under the provision of law or treaty under which the person is claiming U.S. citizenship or non-citizen nationality.
2. (b)Documentary evidence.
   1. (1)Types of documentary evidence of citizenship for a person born outside the United States include:
      1. (i)A certificate of naturalization.
      2. (ii)A certificate of citizenship.
      3. (iii)A Consular Report of Birth Abroad.
   2. (2)An applicant without one of these documents must produce supporting documents as required by the Department, showing acquisition of U.S. citizenship under the relevant provisions of law.