… "Mastering The Chess Openings" by John Watson ...
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-1-p3569.htm
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_1.pdf
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-2-76p3570.htm
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_2.pdf
https://web.archive.org/web/20140627115737/http://www.chesscafe.com/text/hansen99.pdf
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-3-76p3571.htm
https://web.archive.org/web/20140626220240/http://www.chesscafe.com/text/hansen117.pdf
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_3.pdf
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-4-76p3572.htm
https://web.archive.org/web/20140627070808/http://www.chesscafe.com/text/hansen137.pdf
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_4.pdf
… "Chess Structures: A Grandmaster Guide" by Mauricio Flores Rios ...
https://chessbookreviews.wordpress.com/tag/chess-structures-a-grandmaster-guide/
https://www.newinchess.com/media/wysiwyg/product_pdf/7495.pdf