Perry, A. (2018). Twenty-one days: A Daniel Pitt novel (First Edition.). Ballantine Books.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रPerry, Anne. Twenty-one Days: A Daniel Pitt Novel. First Edition. New York: Ballantine Books, 2018.
एमएलए (8वां संस्करण) प्रशस्ति पत्रPerry, Anne. Twenty-one Days: A Daniel Pitt Novel. First Edition. Ballantine Books, 2018.
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