Comparative characteristics of the qualitative state of humus compounds of virgin and cultivated soils by desorption mass spectrometry method - B. B. Paljanitsa; M. F. Berezhnjak; O. L. Tonkha; K. Laslo; A. Menikhard; A. Tot; O. A. Dudik; T. V. Chernjavskaja; T. V. Kulik (Surface, 2012)