Alconera, V. P. (2009). Obligations & contracts (2009 ed.). Central Book Supply.
Chicago-viite (17. p.)Alconera, Virgilio P. Obligations & Contracts. 2009 ed. Quezon City: Central Book Supply, 2009.
MLA-viite (9. p.)Alconera, Virgilio P. Obligations & Contracts. 2009 ed. Central Book Supply, 2009.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.