CHEMICAL AND MINERAL-COMPOSITION OF THE CLAY OF GLEY SOILS IN THE KOLKHIDA LOWLAND Статья VUKOLOV N.G., GRADUSOV B.P. Soviet Soil Science. Том 12. 1980. С. 199-209
CONTENT AND RATIO OF GROUPS AND FORMS OF IRON COMPOUNDS IN THE VOLCANIC SOILS OF COSTA-RICA Статья VEGA O.T. Soviet Soil Science. Том 12. 1980. С. 545-553