Why are the jeongseok changing that were once correct?
It is because the advantage point system has changed.
It follows that black seeks more in the opening
and that the old jeongseok have had to be reanalyzed.
The old jeongseok and haengma are newly transformed and
ongoing changes.

This book deals with popular shapes often seen in real games
and in recent matches.
If you want to learn the basic shapes,
real games will be a lot of help.