Não informado. (1963). Ball and Roller Bearing Engineering. Fag kugelfischer Georg Schafer.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Ball and Roller Bearing Engineering. Schweinfurt, Alemanha: Fag kugelfischer Georg Schafer, 1963.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Ball and Roller Bearing Engineering. Fag kugelfischer Georg Schafer, 1963.
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