(1981). 1981 constitutional amendments. U.P. Law Center.
Cita Chicago (17th ed.)1981 Constitutional Amendments. Quezon City: U.P. Law Center, 1981.
Cita MLA (9th ed.)1981 Constitutional Amendments. U.P. Law Center, 1981.
Atenció: Aquestes cites poden no estar 100% correctes.