(E21) Korchnoi
1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 c5 5.d5
(E21) Euwe
1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 c5 5.d5 Ne4