My solution:

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[go]$$Bc
$$ | . . X , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . X O . . . . . .
$$ | . . . . O . O O . .
$$ | . . X X . . X . . ,
$$ | . X O . O O X . O .
$$ | . X O . 2 X . X O .
$$ | . . 3 . 1 . . . . .
$$ ---------------------[/go]

Click Here To Show Diagram Code

[go]$$Bc
$$ | . . X , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . X O . . . . . .
$$ | . . . . O . O O . .
$$ | . . X X 7 . X . . ,
$$ | . X O 3 O O X . O .
$$ | . X O 2 4 X . X O .
$$ | . . 5 6 1 . . . . .
$$ ---------------------[/go]

But this is not even mentioned in the book. Its solution is

Click Here To Show Diagram Code

[go]$$Bc
$$ | . . X , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . X O . . . . . .
$$ | . . . . O . O O . .
$$ | . . X X . . X . . ,
$$ | . X O . O O X . O .
$$ | . X O 2 3 X . X O .
$$ | . . 1 . . . . . . .
$$ ---------------------[/go]

which I had discarded because I couldn't find a good continuation after

Click Here To Show Diagram Code

[go]$$Bc
$$ | . . X , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . X . . . . . . .
$$ | . . X O . . . . . .
$$ | . . . . O . O O . .
$$ | . . X X . . X . . ,
$$ | . X O . O O X . O .
$$ | . X O . . X . X O .
$$ | . . 1 2 . . . . . .
$$ ---------------------[/go]

What am I missing?

Your kosumi does seem better than the book's hane, after which I can only find a ko to connect (cut above, capture, atari, connect above, take ko). But in your sequence you made quite a big mistake later and should swap 3 and 4 so you can connect without losing the f2 stone which is a lot of points.