Estolas, J. V., Salvador, S. M., & Villalva, Z. S. (1989). Marketing research for Filipinos. National Book Store.
Lua i Stíl Chicago (17ú heag.)Estolas, Josefina Villanueva, Samuel M. Salvador, agus Zenaida S. Villalva. Marketing Research for Filipinos. Metro Manila: National Book Store, 1989.
Lua MLA (9ú heag.)Estolas, Josefina Villanueva, et al. Marketing Research for Filipinos. National Book Store, 1989.
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