411 REFERENCE · Wikibooks
Chess Opening Theory/1. d4/1...d5/2. c4/2...e6/3. Nc3/3...Nf6/4. Bg5/4...Be7/5. e3/5...O-O/6. Nf3
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Queen's Gambit Declined D55-69 Orthodox variation
6. Nf3
White proceeds with normal development. Black now has two options.
Go into the classical variation with /6...Nbd7/.
Go for either Lasker's defense or the Tartakower variation with /6...h6/.
Theory table
6...h6 7. Bh4 Classical variation 6...Nbd7
References
See also