For anybody wanting to try Nimzowitsch books, let me mention that the
most common English version of _Blockade_ found in online used
bookstores is indeed in algebraic notation, although neither the front
nor back covers mentions that.

My copy (algebraic notation): "Blockade", Chess Enterprises publisher,
isbn 0-931462-07-x, 1983 revised version, editor B.G. Dudley,
softcover Yellow with brown Knight covered by yellow pawn.

In title page it calls itself the third printing, on the back cover it
says fourth printing.

"Clearly instructs the chess student on the proper handling of pawn
majorities, both qualitative and quantitative; center and flank; the
creation of passed pawns, and the defense against passed pawns by
restriction, and as a climax - the Blockade!"

I agree with the word "clearly", it is easy for relative beginners
(like me) to follow along with what the author is trying to teach. His
other two books mentioned are a bit too deep for me right now.