Não informado. (1920). Station circular. Oregon Agricultural Experiment Station.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Station Circular. Corvallis, Ore: Oregon Agricultural Experiment Station, 1920.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Station Circular. Oregon Agricultural Experiment Station, 1920.
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