A48 - 1. d4 Nf6 2. Nf3 g6 3. Bf4 Bg7 4. e3 - London System


London System (A48)
Coups: 1. d4 Nf6 2. Nf3 g6 3. Bf4 Bg7 4. e3
├── A48 - 1. d4 Nf6 2. Bf4 g6 3. e3 Bg7 4. Nf3 O-O - London System (2)
└── A48 - 1. d4 Nf6 2. Nf3 g6 3. Bf4 Bg7 4. e3 d6 5. Be2 O-O - London System, with Be2 (1)