Properties and composition of soil organic matter in forest and arable soils of schleswig holstein 1. comparison of morphology and results of wet chemistry cpmas carbon 13 nmr spectroscopy and pyrolysis field ionization mass spectrometry Beyer, L.; Schulten, H.R.; Fruend, R. Zeitschrift fuer Pflanzenernaehrung und Bodenkunde 155(4): 345-354 1992 https://eurekamag.com/research/007/696/007696071.php