1. Michigan Agric. Exp. Sta. Tech. Bull.;Bouyoucos,1915
2. Bouyoucos, G. J., , , J. Agric. Res., , v. 5, , pp. 141– -172 , 1915, .
3. Curtis, O. F., , , Amer. J. Bot, , v. 24, , pp. 705– -710 , 1937, .
4. Nikiforoff, C. C., , , Soil Sci., , v. 52, , pp. 193– -211 , 1941, ,
5. Smith, W. O., , and H. G., Byers, , , Proc. Soil Sci. Soc. Amer., , v. 3, , pp. 13– -19 , 1918, .