References
- Gordon , W. R. , Schwemmer , S.S. and Hillman , W.S. 1978 . Planta , 140 : 265 – 268 .
- Rehab , F.I. and Wallace , A. 1978 . Commun. Soil Sci. Plant Anal. , 9 : 771 – 778 .
- Wallace , A. , Romney , E.M. and Cha , J.W. 1977 . Commun. Soil Sci. Plant Anal. , 8 : 787 – 790 .