Аннотация:Article analysis consists the list the significance of the main results that were obtained when analyzing the graph-phonetic features of the first Cyrillic books in the XIX century:1.The first Cyrillic books allow us to see how the classification of dialects changed.2.The first Cyrillic books allow you to date the time of phonetic changes.3.The first Cyrillic books make it possible to verify the accuracy of transcription of extinct dialects completed by different authors.4.The first Cyrillic books made it possible to identify phenomena that persist in modern dialects and existed in the XIX century, but previously did not attract the systematic attention of scientists.5.The first Cyrillic books make it possible to clarify the territory where speakers of some dialects had previously lived.6.The first Cyrillic books confirm the reconstruction of the proto-language.7.First books allow us to clarify the reconstruction of the proto-language.8.The first Cyrillic books allow us to establish who was the true creator of literary languages.