The present edition of Tchaikovsky's selected piano pieces is based on his Collected Works (Vols. 51a, 51b, 52 and 53). Since the composer often modified the music while preparing it for further publications, we have used also some other editions of Tchaikovsky's works, including those revised by Tchaikovsky for Jurgenson.
The author's marks related to tempo, dynamics, phrasing, fingering and pedal — in short, all the marks found in the original text — are printed in large characters. All the supplementary marks, both those from Jurgenson's new edition (most probably approved by Tchaikovsky himself) and those added by the present editors, are printed in small characters.
(from the preface to the first edition)

1. January. By the Hearth

2. February. Shrovetide

3. March. Lark's Song

4. April. Snowdrop

5. May. White Nights

6. June. Barcarole

7. July. Reaper's Song

8. August. Harvest

9. September. Hunt

10. October. Autumn Song

11. November. In the Troika

12. December. Christmas-Tide