Kalalang, I. P. Z. (2011). Kalalang-Ong level of optimism scale. University of the Philippines Diliman Extension Program in Pampanga.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रKalalang, Irish Pauline Z. Kalalang-Ong Level of Optimism Scale. Pampanga: University of the Philippines Diliman Extension Program in Pampanga, 2011.
एमएलए (9वां संस्करण) प्रशस्ति पत्रKalalang, Irish Pauline Z. Kalalang-Ong Level of Optimism Scale. University of the Philippines Diliman Extension Program in Pampanga, 2011.
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