The map is amazing!I just want to add a comment on Poles in Lithuania and Belarus. I don't know what sources you used, but I myself being Lithuanian was able to access some native sources that cover this topic. Leaving the historical circumstances aside, most Poles in Belarus, as you mentioned before, speak Belarusian language, rather than Polish. According to your map, in Lithuania all Poles speak Polish, which is only half-true. Lithuanian and Belarusian Poles belong to the same ethnic group, whose territory is divided between Lithuania and Belarus (the formation of this group is another story). As in Belarus, most Poles in Lithuania also speak a dialect of Belarusian, the same one as in Belarus. There are two sources for that:firstly, most natives from Poland who visit Lithuania, say that they can hardly communicate with local Poles;secondly, in 1990 one of the most famous Lithuanian cartographers and ethnologists, dr. Petras Gaučas, made a thorough research of Eastern Lithuania's linguistic and ethnic situation, which revealed, that in fact, most Lithuanian Poles spoke Belarusian. In their book 'Lietuvos Rytai' they presented a map that I include.Here pink represents a local dialect of Belarusian that Poles in both Lithuania and Belarus speak (called 'po prostu'). Yellow is the real Polish language area while green is Lithuanian language area. Both non-Lithuanian language areas have shrunk since 1990 because of mixed marriages, but the general picture stays the same - most Poles still speak Belarusian at home in Lithuania.