E53: Nimzo-Indian, 4.e3, main line with ...c5

E53 Sub-variants:

• Nimzo-Indian, 4.e3, main line with ...c5
  1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 O-O 5. Nf3 d5 6. Bd3 c5
• Nimzo-Indian, 4.e3, Keres variation
  1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 O-O 5. Nf3 d5 6. Bd3 c5 7. O-O b6
• Nimzo-Indian, 4.e3, Gligoric system with 7...Nbd7
  1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 O-O 5. Nf3 d5 6. Bd3 c5 7. O-O Nbd7