Cita APA (7th ed.)

(1973). Zamboanga-Sulu barter trade. s.n.

Cita Chicago (17th ed.)

Zamboanga-Sulu Barter Trade. [S.l: s.n, 1973.

Cita MLA (9th ed.)

Zamboanga-Sulu Barter Trade. s.n, 1973.