[full article, abstract in Russian; abstract in Lithuanian and English]
The author of this article shows on concrete patterns how the systematization and analysis of rare or unique elements of Russian epic songs (bylinas) help in solving some scientific problems. Non-standard details, formulas, personal names serve as reliable indicators that the texts are changed by recorders or editors, that they are dependent on books or even falsified. Besides, they help to reveal variants related by birth and to determine their genealogic relationship. Often, they reflect details of early medieval history or life conditions, contain poetic forms similar to the literary monuments of ancient Russia.
However, their analysis must be done on the background of all recorded texts of bylinas. Authors who use only limited variants of epic songs (V. P. Anikin, B. A. Rybakov and others) sometimes come to doubtful or erroneous conclusions.