Effects of the Addition of Foils Produced from Polyethylene and Maize Starch to Composted Biomass on Quantitative and Qualitative Composition of Humic Compounds and Optic Parameters of Humic Acids - Gondek, Krzysztof; Tabak, Monika; Koncewicz-Baran, Małgorzata; Kopeć, Michał (Polish journal of environmental studies, 2015)