Ehret. Footprints in Stone. The University of Alabama Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रEhret. Footprints in Stone. The University of Alabama Press.
एमएलए (9वां संस्करण) प्रशस्ति पत्रEhret. Footprints in Stone. The University of Alabama Press.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.