PLANT NUTRIENTS 15 



References 



BRENCHLEY, WINIFRED E. "Inorganic Plant Poisons and Stimulants," 

 106 pages, 18 figs., Cambridge, 1914. 



HALL, A. D. "Fertilizers and Manures," 384 pages, 7 plates, London, 1909. 



HALL, A. D. "The Book of the Rothamsted Experiments," 294 pages, 49. 

 figs., 8 plates, London, 1905. 



HOPKINS, C. G. "Soil Fertility and Permanent Agriculture," 653 pages, 

 Chicago, 1910. 



HILGARD, E. W. "Soils," 593 pages, 89 figs., New York, 1906. 



LOEW, O "The Physiological Role of Mineral Nutrients," U. S. Depart- 

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 Washington, D. C., 1903. 



RUSSELL, E. J "Soil Conditions and Plant Growth," 243 pages, 13 figs., 

 Monographs on Biochemistry, London, 1917. (3d ed.) 



WHITNEY, M. "A Study of Crop Yields and Soil Composition in Relation 

 to Soil Productivity," U. S. Department of Agriculture, Bureau of Soils, 

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