E23: Nimzo-Indian, Spielmann, Staahlberg variation

E23 Sub-variants:

• Nimzo-Indian, Spielmann, 4...c5, 5.dc Nc6
  1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qb3 c5 5. dxc5 Nc6
• Nimzo-Indian, Spielmann, Karlsbad variation
  1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qb3 c5 5. dxc5 Nc6 6. Nf3 Ne4 7. Bd2 Nxd2
• Nimzo-Indian, Spielmann, San Remo variation
  1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qb3 c5 5. dxc5 Nc6 6. Nf3 Ne4 7. Bd2 Nxc5
• Nimzo-Indian, Spielmann, Staahlberg variation
  1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qb3 c5 5. dxc5 Nc6 6. Nf3 Ne4 7. Bd2 Nxc5 8. Qc2 f5 9. g3