C49Black1 book lines continue
Spanish Variation
Four Knights Game1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5 Bb4 5. O-O O-O 6. d3 Bxc3 7. bxc3 d6
Also known as Four Knights: Double Bishops, 6.d3 Bxc3, Four Knights Game: Spanish Variation, 5. O-O O-O 6. d3 Bxc3.