... Artur Yusupov's books. ...
https://web.archive.org/web/20140708103659/http://www.chesscafe.com/text/review778.pdf
https://web.archive.org/web/20140708103321/http://www.chesscafe.com/text/review699.pdf
https://web.archive.org/web/20131010091053/http://www.chesscafe.com/text/review834.pdf
https://web.archive.org/web/20140708085817/http://www.chesscafe.com/text/review843.pdf
... "Chess Tactics From Scratch...." by Martin Weteschnik ...
https://web.archive.org/web/20140708091717/http://www.chesscafe.com/text/review851.pdf
"Techniques of Positional Play" by Valeri Bronznik and "What It Takes To Become A Chessmaster" by Andrew Soltis.
I second the Bronznik book. Its very good...
"Techniques of Positional Play" by Valeri Bronznik
http://www.amazon.com/Techniques-Positional-Play-Practical-Methods/dp/9056914340/ref=sr_1_1?ie=UTF8&qid=1460727450&sr=8-1&keywords=technique+positional
Also at your level, you might like...
"Chess Tactics From Scratch...." by Martin Weteschnik
http://www.amazon.com/Chess-Tactics-Scratch-Understanding/dp/1907982027/ref=sr_1_1?ie=UTF8&qid=1460727537&sr=8-1&keywords=martin+weteschnik
Both books are targeted to the more advanced player...