Bärenreiter Urtext Edition 26, published by Zen-On Music Publishing Co., Handel: 6 Sonatas for Violin and Basso Continuo. It's only about 6mm thick, so it looks bent in the photo. I can't play the violin, but I bought it for reference, and ended up not using it. The spine is a bit sun-faded, but otherwise it's as good as new.