United States. Department of the Interior. Office of the Solicitor & United States. Department of the Interior. Division of Information and Library Services. Law Branch. (1981). Unpublished M-opinions of the Solicitor, U.S. Department of the Interior. [Department of the Interior].
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)United States. Department of the Interior. Office of the Solicitor و United States. Department of the Interior. Division of Information and Library Services. Law Branch. Unpublished M-opinions of the Solicitor, U.S. Department of the Interior. [Washington, D.C.]: [Department of the Interior], 1981.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)United States. Department of the Interior. Office of the Solicitor و United States. Department of the Interior. Division of Information and Library Services. Law Branch. Unpublished M-opinions of the Solicitor, U.S. Department of the Interior. [Department of the Interior], 1981.