The map is a collection of many maps of regional dialects of different languages. Therefore, the borders between languages might not match at all places the one normally present for that language because it overlaps with a border from other language's map. This map was made only by overlaying screenshots of maps, so it should not be used for precise determination. Note that in some areas other (non-slavic) languages might also be spoken or even prevailing (e. g. Kosovo, Hungary and Romania) The coast and the border were taken from Eurostat (https://ec.europa.eu/eurostat/web/gisco/geodata/reference-data/administrative-units-statistical-units/countries). Map of Slovene dialects and Slovene-Croatian border is based on this map. Borders between Serbo-Croatian supradialects are based on (Kapović, 2015 pp.50–51). Chakavian borders are based on (Kapović, 2015, p. 43), Schakavian, Torlakian and Shtokavian are based on (Kapović, 2015, pp. 40–41). Kajkavian is based on Lončarić's map with addition of (Kapović, 2015 p. 46). Burgenland croatian is based on this file while Molise Slavic is based on its Wikipedia page as of April 2023. Border with Macedonian/Bulgarian is based on Kapović's map.

• Kapović, Mate (2015) (chorvatština) Povijest hrvatske akcentuacije, Záhřeb: Zaklada HAZU, p. 50 ISBN: 978-953-150-971-8.

Bulgarian is based on the interactive map.