Askwith, R. (2019). Unbreakable: The woman who defied the Nazis in the world's most dangerous horse race (First Pegasus Books hardcover edition.). Pegasus Books.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रAskwith, Richard. Unbreakable: The Woman Who Defied the Nazis in the World's Most Dangerous Horse Race. First Pegasus Books hardcover edition. New York: Pegasus Books, 2019.
एमएलए (8वां संस्करण) प्रशस्ति पत्रAskwith, Richard. Unbreakable: The Woman Who Defied the Nazis in the World's Most Dangerous Horse Race. First Pegasus Books hardcover edition. Pegasus Books, 2019.
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