Ibarra, M. C. A., Leung, M. F. P., & Magpili, L. M. M. (1992). A Work study on Playpen Export Philippines. College of Engineering.
Chicago-viite (17. p.)Ibarra, Ma. Celeste A., Ma. Felicia P. Leung, ja Luna Mylene M. Magpili. A Work Study on Playpen Export Philippines. Diliman, Quezon City: College of Engineering, 1992.
MLA-viite (9. p.)Ibarra, Ma. Celeste A., et al. A Work Study on Playpen Export Philippines. College of Engineering, 1992.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.