SGEM 2019 : 19th international multidisciplinary scientific geoconference SGEM 2019, 30 June - 6 July, 2019, Albena, Bulgaria. 19, Water resources, forest, marine and ocean ecosystems. Soil forest ecosystems . Sofia :  STEP92 Technology , 2019 . 799 s . ISBN 978-619-7408-82-9 .