Trio, J. K., Valencia, C., Manacsa, R., & Flor, R. (1990). Friendly grocer: Amidst tough competition. UP College of Engineering.
Chicago-viite (17. p.)Trio, John Kenneth, Carlos Valencia, Roberto Manacsa, ja Roger Flor. Friendly Grocer: Amidst Tough Competition. Quezon City: UP College of Engineering, 1990.
MLA-viite (9. p.)Trio, John Kenneth, et al. Friendly Grocer: Amidst Tough Competition. UP College of Engineering, 1990.
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