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Here are some chess puzzles from the QGA, Classical, 6...a6 (ECO D27).

1.d4 d5 2.c4 dxc4 3.Nf3 Nf6 4.e3 e6 5.Bxc4 c5 6.O-O a6
Solutions are between the brackets under each puzzle.
Drag your cursor from one bracket to the other.
White to move and win except where noted.
a) 
Herman Mattison vs Savielly Tartakower, Budapest, 1926
r1b1k2r/2q2ppp/p1n1pn2/1pb5/3N4/2N1P3/PP2BPPP/R1BQ1RK1 w kq - 0 1
[ Nxc6 if Qxc6 Bf3 ]
b) 
A V Gulbrandsen vs Petar Velikov, Copenhagen, 1982
r5k1/1b1rbppp/p1n1pn2/1p6/1P6/PN1BPN2/1B3PPP/2RR2K1 w - - 0 1
[ Bxf6 if Bxf6 Bxh7+ ]
c) 
Carsten Hoi vs Imrich Cervenka, Trnava, 1987
2r1k2r/4bppp/p1n5/1p1p4/5B2/5N2/PP3PPP/2R1R1K1 w k - 0 1
[ Nd4 Na7 Nf5 Rxc1 Rxc1 Bd8 Be3 ]
d) 
Enrique Scarella vs Walter Schulmann, Villa Ballester, 1991
2r1k2r/1b3ppp/p3pn2/q1n5/Pp6/3BB3/1P1N1PPP/2RQ1RK1 w k - 0 1
[ Rxc5 if Rxc5 Nb3 ]
e) 
Igor Naumkin vs JL Llapasset, Asti, 1997
r1br2k1/2q2ppp/p1p5/6N1/P7/8/1P2QPPP/R2R2K1 w - - 0 1
[ Qe5 ]
1c) 
Carsten Hoi vs Imrich Cervenka
D27 Puzzles, Part II.
White to move and win except where noted.
a) 
Bo Rylander vs Bernt Lundgren, Malme, 1998
r1b2rk1/1p2bppp/p3p3/q2n2B1/P7/1QN2N2/1P3PPP/R3R1K1 w - - 0 1
[ Nxd5 if Bxg5 Nb6 Rb8 Re5 ]
b) 
White mates in 3.
Glenn Flear vs Jean-Louis Sabatie, Creon, 1999
r3kb1r/1p3ppp/p1n2n2/4p1N1/2B3b1/1P2P3/P4PPP/RNBR2K1 w kq - 0 1
[ Bxf7+ Ke7 Ba3+ ]
c) 
Oleg Boginin vs Yuri Drozdovskij, Sevastopol, 2000
r4rk1/1bq2ppp/ppn1p3/2bn4/P7/2NBPN2/1P1BQPPP/2RR2K1 w - - 0 1
[ Nxd5 exd5 b4 Bd6 b5 ]
d) 
Valentin Abramov vs Alexey Ivanov, St. Petersburg, 2003
r1q2rk1/1b2bppp/ppn5/2pBN3/P7/1P2P3/1B3PPP/R2Q1RK1 w - - 0 1
[ Nd7 ]
e) 
Clovis Vernay vs Stanislav Demeanciuc, Herceg Novi, 2006
r1br2k1/1pq1bppp/p1n2B2/8/P1p5/2N2N2/1P2QPPP/R2R2K1 w - - 0 1
[ Bxe7 if Nxe7 Qe5 ]
2a) 
Bo Rylander vs Bernt Lundgren
D27 Puzzles, Part III.
Black to move and win.
a) 
Oleg Yewdokimov vs Adolf Herzog, Austria, 1991
r3k2r/bb3pp1/p3p3/1p2n3/PP1N2P1/2N1P3/1B3PP1/R4RK1 b kq - 0 1
[ ...Bxd4 if exd4 Nf3+ mates ]
b) 
Aleksander Pavlov vs Valentin Vlassow, Sosnovy Bor, 2002
r3k2r/1bq2pp1/p3p3/1p1nb1N1/3nB3/6P1/PP3P1P/RNBQ1RK1 b kq - 0 1
[ ...Qxc1 Qxc1 Ne2+ Kh1 Nxc1 Rxc1 Bxb2 ]
c) 
Roth vs Carsten Pieper-Emden, Bad Lauterberg, 1981
r4r1k/1p4pp/p1n2n2/q1b5/P1BpNB2/5Q2/1P3PPP/R2R2K1 b - - 0 1
[ ...Nxe4 if Qxe4 Rae8 Qf3 Ne5 ]
d) 
Marek Kolasinski vs Petr Spacek, Prague, 1989
1r1q1rk1/1b1nbppp/p3pn2/8/Pp2P3/3B1NQ1/1P1N1PPP/R1BR2K1 b - - 0 1
[ ...Nh5 Qg4 Ndf6 Qh4 Qxd3 ]
3b) 
Aleksander Pavlov vs Valentin Vlassow
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