I searched and agree it seems hard to find. However, one link shows several pages from the German language edition and it seems to just be multiple diagrams of tactical problems with no text other than standard Informant symbols.
I don't think you would need to understand German.
I have the english copy in ebook format I will post the link. It is one of the best book on tactics btw if you need any book just pm me I have many book in pdf format :)
Here is the link:- http://www.filedropper.com/pdfchesstacticstraining-nikolaishumilin
Just click on download this file and then enter captca and the download of this file will begin. This is very old scanned copy. Preface is in both lanugage and after that it is english
Here is the site where you can download the digital version of the COMPLETE ebook...in cbv or pgn mode...
Go to the "Free db books" folder and voila...note, you will be quite distracted by the many other books available...also, check out the following:
Ossmitz did some amazing work before his passing...there are some that are password protected...however, one in particular is worth exploring...Euwe and Kramer's Middle Game (two volumes)...note the password is found in the book itself...thus if you have the book (s) (note, you will need volume 2)...you will have the password. This is probably the best middlegame book out there...very classic in nature...
Anyway, your original question is answered in full...I too am very, very impressed with Shumilin's work...appears to be Russian...suspect it is/has been used by very strong club players to advance to the next level....ENJOY!
I was told that this book was great by Nikolai Shumilin. It is not available. Does anyone know of an English copy? An e-book or any other way to access it? Do others feel this is a must have, or is some other book just as good or better? Thanks, Duane