Problem diagram.
Black's response to the marked stone?

Source:
Match the Joseki to the Fuseki , Sakiyama Toshio 9p
Go World #4, Nov-Dec 1977, pp. 39-44

Solution follows    (or click here to download SGF)

Correct.
The attachment joseki at 1 is correct here. Through 5, Black's joseki works well with the marked Black stone to build a moyo. In addition, White's marked stone is now badly located to protect the weakness at A. If the marked White stone was 1 space higher, Black could not cut at A.

See the next diagram.

Follow up.
Later, after the preceding diagram, Black's cut at 7 becomes very effective. White must capture starting with 8, because if White ataris from above, Black would simple extend out to the left, after which White's position would be very bad.

Starting with 11, Black has a string of forcing moves. Through 16, White has become overconcentrated in gote. In particular, the marked White stone has almost become a wasted move. Meanwhile, Black's thickness on the right threatens a moyo.

Failure.
White can avoid the weakness in the previous variation by jumping into the corner with 4. But Black can play solidly at 5. After jumping to 13, Black has a vast moyo and a straightforward position. And White is still overconcentrated at the top.

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