Jurgen This seems indeed very much like exercise 90, however the variation no longer works. White can no longer play K18 (as the marked black stone is already there), which results in a false eye being formed.
Jasonred : So, now black can kill white because of that stone eh?
Jurgen : Yes white is dead in this variation, thanks for making the diagrams. Of course if black mistakenly plays the original variation then white lives.