APA (7e ed.) Bronvermelding

De Leon, H. S. (1969). The law on obligations and contracts. s.n.

Chicago (17e ed.) Bronvermelding

De Leon, Hector S. The Law on Obligations and Contracts. [Manila: s.n, 1969.

MLA (9e ed.) Bronvermelding

De Leon, Hector S. The Law on Obligations and Contracts. s.n, 1969.