如歌的行板其实是柴可夫斯基String Quartet No. 1 in D major 一个乐章. It was the first of Pyotr Ilyich Tchaikovsky's three string quartets, and his Opus 11. The quartet has 4 movements:

1. Moderato e semplice (D major)
2. Andante cantabile (B♭ major)
3. Scherzo. Allegro non tanto e con fuoco – Trio (D minor)
4. Finale. Allegro giusto – Allegro vivace (D major)

The melancholic Andante cantabile movement has become famous, and was founded on a folk-song the composer heard whistled by a house painter. When the quartet was performed at a tribute concert to Leo Tolstoy, the author was said to have been brought to tears by this movement.

这个四人演奏也不错