References
- Swaine , D. J. 1955 . The trace‐element content of soils , Bucks, , England : Commonwealth Agricultural Bureaux, Farnham Royal . Commonwealth Bureau of Soil Science. Technical Communication No. 48.
- Pratt , P. F. 1966 . “ Titanium ” . In Diagnostic Criteria for Plants and Soils , Edited by: Chapman , H. C. 478 – 479 . Riverside, California : Division of Agricultural Sciences, University of California .
- Arnon , D. I. and Stout , P. R. 1939 . The essentiality of certain elements in minute quantity for plants with special reference to copper . Plant Physiol. , 14 : 371 – 375 .