De Leon, H. S. (1994). The National internal revenue code annotated: (P.D. No. 1158, as amended) (5th ed.). Rex Book Store.
Dyfyniad Arddull ChicagoDe Leon, Hector S. The National Internal Revenue Code Annotated: (P.D. No. 1158, as Amended). 5th ed. Manila: Rex Book Store, 1994.
Dyfyniad MLADe Leon, Hector S. The National Internal Revenue Code Annotated: (P.D. No. 1158, as Amended). 5th ed. Rex Book Store, 1994.
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