19th International conference of humic substances and their contribution to the climate change mitigation : book of abstracts, 16-21 September, 2018, Albena Bulgaria / editor Ekaterina Filcheva. -- 1st. ed. -- Sofia, Bulgarian Humic Substances Society 2018. -- 372 s. -- ISBN 978-619-90189-3-4 (brož.). pôda * humínové látky * pôdna organická hmota