This revised edition was prepared after comparison of the last printed edition with all known manuscript sources. These included a sketch of the work, its "final" manuscript, a duplicate of this with some changes by the composer (used in the engraving), a copy of the final manuscript that has been converted to be the engraving copy of the parts and a copy of the first printed miniature score with some corrections by the composer. Thin E Majority of changes concern mechanical features and precision of details (e.g. articulation of beams, the point where a dynamic change occurs, etc.). Capital letters in circles are reference points corresponding to the analysis of the composition by Bela Bartók. This analysis is enclosed in facsimile to the present revised edition.