Main, M., Hill, N., Canfield, J., & Proctor, B. (2019). The lost secret: Unlocking the hidden chapters of Napoleon Hill's think and grow rich. Waterside Productions.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रMain, Monica, Napoleon Hill, Jack Canfield, और Bob Proctor. The Lost Secret: Unlocking the Hidden Chapters of Napoleon Hill's Think and Grow Rich. Cardiff-by-the-Sea, CA: Waterside Productions, 2019.
एमएलए (8वां संस्करण) प्रशस्ति पत्रMain, Monica, et al. The Lost Secret: Unlocking the Hidden Chapters of Napoleon Hill's Think and Grow Rich. Waterside Productions, 2019.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.