Maxim Blokh Books - Suggestion required

Hi,

I have finish going  through 1001 combinations by Maxim Blokh in a few weeks(2nd revision).

Following are books written by Maxim Blokh. 

a) Combinational Motif

b) Art of Combination

c) 600 Combinations

1) Are all these books the same or if they have different material, in which order should they be studied ?

2) On which book is the CT Art based on ?

3) Are there other tactics books as good as these books ?

4) How should these books be studied ? Any tips ?

Thank you

I can only answer question 2; CT-ART was/is based on the book Combinative Motifs. It contains more than 1400 tactics, and I would imagine that one contains most of the tactics from the other books.