I got it first time!  Great puzzle, thx

I tend to agree with you.  These are from a book written by a US National Master.  He first produced a book of "Combinations" and then made this smaller book from it.  Some are easier than others and I think the great variation in difficulty suggests he has lost touch with the weaker player's thought processes.

These positions are too difficult for a beginer. One can only imagine that later examples must be even more difficult. These exercises are more suitable for advanced players with rating around 1600.