Groeg, O. J. (1979). Who's who in technology: Ed. Austria, Germany, Switzerland ; a biographical encyclopedia / ed. by Otto J. Groeg. Who's who Book u. Publ. Ges..
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रGroeg, Otto J. Who's Who in Technology: Ed. Austria, Germany, Switzerland ; a Biographical Encyclopedia / Ed. by Otto J. Groeg. Wörthsee b. München: Who's who Book u. Publ. Ges., 1979.
एमएलए (8वां संस्करण) प्रशस्ति पत्रGroeg, Otto J. Who's Who in Technology: Ed. Austria, Germany, Switzerland ; a Biographical Encyclopedia / Ed. by Otto J. Groeg. Who's who Book u. Publ. Ges., 1979.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.