Helfrich M, Ludwig B, Potthoff M, Flessa H (2008) Effect of litter quality and soil fungion macroaggregate dynamics and associated partitioning of litter carbon and nitrogen. Soil Biol Biochem 40(7):1823-1835, DOI:10.1016/j.soilbio.2008.03.006

Flessa H, Amelung W, Helfrich M, Wiesenberg GLB, Gleixner G, Brodowski S, Rethemeyer J, Kramer C, Grootes PM (2008) Storage and stability of organic matter and fossil carbon in a Luvisol and Phaeozem with continuous maize cropping: a synthesis. J Plant Nutr Soil Sci 171(1):36-51, DOI:10.1020/jpln.200700050

Helfrich M, Flessa H, Mikutta R, Dreves A, Ludwig B (2007) Comparison of chemical fractionation methods for isolating stable soil organic carbon pools. Eur J Soil Sci 58(6):1316-1329, DOI:10.1111/j.1365-2389.2007.00926.x

Helfrich M, Ludwig B, Buurman P, Flessa H (2006) Effect of land use on the composition of soil organic matter in density and aggregate fractions as revealed by solid-state 13 C NMR spectroscopy. Geoderma 136(1-2):331-341, DOI:10.1016/j.geoderma.2006.03.048

Terhoeven-Urselmans T, Michel K, Helfrich M, Flessa H, Ludwig B (2006) Near-infrared spectroscopy can predict the composition of organic matter in soil and litter. J Plant Nutr Soil Sci 169(2):168-174, DOI:10.1002/jpln.200521712

Yamashita T, Flessa H, John B, Helfrich M, Ludwig B (2006) Organic matter in density fractions of water-stable aggregates in silty soil: effect of land use. Soil Biol Biochem 38(11):3222-3234, DOI:10.1016/j.soilbio.2006.04.013

Ludwig B, Helfrich M, Flessa H (2005) Modelling the long-term stabilization of carbon from maize in a silty soil. Plant Soil 278(1-2):315-325, DOI:10.1007/s11104-005-8808-2