58a 



Opyt. Agron. 11: 321-543 (1910); Suprunenko,- Zap. Hovo- 

 Alex. Inst, Selsk. Khoz. i Liesov. 21; 59-63 (1910}; 

 Jonkoy,- Khoziaistvo 5 > : 37-46 (1911); Zhukov,- Zhur. Opyt, 

 Agron. 12: 55E (1911); Jodidi,- Landw. Vers. Stat. 85: 

 359-391 (1914); Vernadskii,- Pedogie 15: 1-21 (1914); 

 Leather,- Jour. Agr. Sci. 7: 240-241 (1915). 



