Maestro, M., & Maestro, G. (1996). What do you hear when cows sing?: And other silly riddles. HarperCollinsPublishers.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रMaestro, Marco, और Giulio Maestro. What Do You Hear When Cows Sing?: And Other Silly Riddles. [New York]: HarperCollinsPublishers, 1996.
एमएलए (8वां संस्करण) प्रशस्ति पत्रMaestro, Marco, और Giulio Maestro. What Do You Hear When Cows Sing?: And Other Silly Riddles. HarperCollinsPublishers, 1996.
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