"Humic acid carbon_unknown method" . . . . "HumAcidC_unkn" . "HumAcidC_unk"@en . "Leenaars J.G.B., A.J.M. van Oostrum and M. Ruiperez Gonzalez, 2014. Africa Soil Profiles Database, Version 1.2. A compilation of georeferenced and standardised legacy soil profile data for Sub-Saharan Africa (with dataset). ISRIC Report 2014/01. Africa Soil Information Service (AfSIS) project and ISRIC - World Soil Information, Wageningen, the Netherlands. See Annex 4." . . .