The Baltic Defense to the Queen's Gambit
In the past many masters have tried to solve Black's problem of developing the Queen's Bishop after blocking it in by 2..e6(1.d4 d5 2.c4 e6). But there is another school that thinks Black should solve the Bishop problem first, with 2..Bf5. A number of them from the Baltic nations were GM Mikenas and GM Keres. The modern generation is lead by GM's Bagirov, Shirov, and Rausis. We believe books have overlooked 1.d4 d5 2.c4 Bf5 or 1.Nf3 d5 2.d4 Bf5 or 1.d4 d5 2.Nf3 Bf5.