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(37) Smith, C. R. 
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(38) Stewart, J. 
1922. Some relations of arsenic to plant growth : Part I. In Soil 
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(40) Stoklasa, J. 
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(41) Stone, G. E. 
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used in exterminating weeds. In Mass. Agr. Exp. Sta. 21st 
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(42) Swain, R. E., and Harkins, W. D. 
1908. Arsenic in vegetation exposed to smelter smoke. In Jour. 
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(43) Swingle, D. B., and Morris, H. E. 
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(44) Thompson, N. F. 
1923. Kill the common barberry with chemicals. U. S. Dept. Agr. 
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(45) Voelcker, J. A. 
1919. Pot-culture experiments, 1919. In Jour. Roy. Agr. Soc. Eng- 
land, v. 80, p. 430-438, illus. 
(46) Wilcox, E. V. 
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(47) 1915. Summary of investigations. Miscellaneous. In Hawaii Agr. 
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(48 j Wober, A. 
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2, p. 161-178. 
