U.S. Soil Conservation Service. (1939). Conservation of the soil; a unit for elementary schools developed by the Fairbrother-Rossell School, in cooperation with the Soil Conservation Service, USDA. s.n.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रU.S. Soil Conservation Service. Conservation of the Soil; a Unit for Elementary Schools Developed by the Fairbrother-Rossell School, in Cooperation with the Soil Conservation Service, USDA. Washington, D. C: s.n, 1939.
एमएलए (9वां संस्करण) प्रशस्ति पत्रU.S. Soil Conservation Service. Conservation of the Soil; a Unit for Elementary Schools Developed by the Fairbrother-Rossell School, in Cooperation with the Soil Conservation Service, USDA. s.n, 1939.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.