(;
AB[as][er][bq][eq][gq][iq][bp][cp][dp][pp][bo][bn][pn]
AW[cs][br][dr][cq][dq][kq][nq][ep][eo][an][cn][dn][bm][cl]
C[Black plays.

Source:
     Tesuji Dictionary, by Segoe Kensaku & Go Seigen]
(;
B[ar]
C[Black cannot allow White to make a 2nd eye.];
W[aq];B[ap];W[do];B[es];W[ds]
C[Black's situation continues to look hopeless.]
(;
B[bs]
C[Black's saving resource.];
W[aq]
(;
B[bs];W[as];B[ar]
C[Black has salvages a ko for the group.]
)
    (;
    B[ar]
    C[Fails.];
    W[bs]
    C[White protects the weakness and Black's group dies.]
    )
)
    (;
    B[aq]
    C[Black doesn't have time to set up this straightforward atari from the inside.];
    W[co]
    C[Black is short of liberties.]
    )
)
    (;
    B[es]
    C[Also works by transposing into the main line.]
    )
)

