1. Blaylock, A. D., Belden, K. and Hough, H. W. 1996.Guide to Wyoming Fertilizer Recommendations, 60Laramie, WY: University of Wyoming Cooperative Extension.
2. Gavlak, R., Horneck, D., Miller, R. O. and Kotuby-Amacher, J. 2003.Soil Plant and Water Reference Methods for the Western Region, 2nd, 199Oregon: Western Region Extension Publication Corvallis.
3. Iron Deficiency Decreases the Fe(III)-Chelate Reducing Activity of Leaf Protoplasts