Downing, D. (2010). Barron's E-Z trigonometry ([4th ed.].). Barron's Educational Series.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रDowning, Douglas. Barron's E-Z Trigonometry. [4th ed.]. Hauppauge, N.Y.: Barron's Educational Series, 2010.
एमएलए (8वां संस्करण) प्रशस्ति पत्रDowning, Douglas. Barron's E-Z Trigonometry. [4th ed.]. Barron's Educational Series, 2010.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.