SGEM SGEM 2021. 21st International Multidisciplinary Scientific GeoConference. Volume 21. Green Design and Sustainable Architecture; iss. 6.2 7-10 December 2021, Viedeň, Rakúsko,. -- 1. vydanie. -- Sofia, Bulharsko : SGEM World Science, 2021. -- 518 s. -- (Iss. 6.2 - SGEM International Multidisciplinary Scientific GeoConference). -- ISBN : 978-619-7603-36-1. -- ISSN : 1314-2704.