The Bogoljubov Indian Defence, usually called in short the Bogo-Indian, is closely related to the Queen’s Indian and the Nimzo-Indian, but it has not been researched nearly as deeply. At the highest level, 3...Bb4+ was introduced to practice in the 1920s by Efim Bogoljubov (1889–1952), who contested the world title against Alexander Alekhine in 1929 and 1934. Nowadays the move has been played above all by Korchnoi, Yusupov and Adams. Because 4.Nc3 now leads directly to the Kasparov Variation of the Nimzo-Indian, only 4.Nbd2 and 4.Bd2 are of any independent significance. 4.Nbd2 looks a little unnatural since it shuts in the Bc1 and since the knight exerts less control over the centre than it would from c3, but White is counting on the fact that a2-a3 will either bring him the bishop pair or force the bishop to retreat. Black has several possible setups here. 4.Bd2 parries the check and attacks the Bb4, which can be defended with 4...c5, 4...a5 or 4...Qe7.