A few years back Chris Ward, one of the most humorous and competent writers around, wrote the lower-level introductory book STARTING OUT: THE NIMZO-INDIAN. He presented the opening from Black's point of view (and he has also done a video advocating Black's side of the Nimzo). Ward has now has laid out (suggested?) a detailed system from the White side in NIMZO-INDIAN KASPAROV VARIATION. The latter begins with the move 4.Nf3, intending to play either 4...c5 5.g3 or 4...b6 5.Bg5 (4...0-0 5.Bg5 is a little easier for White to handle, and 4...d6 5.Qc2 normally ends up looking like one of the 4.Qc2 lines, but with somewhat more flexibility for White).

Ward also discusses the interesting 4...b6 5.Qb3 which enjoys spurts of popularity amongst top grandmasters. In general, the author is so attached to his favorite Nimzo-Indian that anything he suggests for White should be taken seriously. Taking a quick look at STARTING OUT: THE NIMZO-INDIAN, I see that there's no serious comparison between the books because STARTING OUT is too elementary, e.g., Ward had given 5.Qb3 a5 there and analyzed only 6.a3 a4! etc., but in his new book he thinks 5...a5 is  possibly “detrimental” giving only 6.Bg5 and 6.g3 (and not 6.a3).

I briefly considered comparing Ward's 4.Nf3 repertoire with JOHN EMM'S NIMZO-INDIAN GUIDE, reviewed on this site by Silman; however, Ward not only cites that book but worked with Emms on the opening! Comparisons aside, it's so hard to find anything effective (or even interesting!) versus the Nimzo-Indian these days that players of White might have a good time using the ideas in this book. To his credit, Ward doesn't pretend that his system produces any advantage versus strong play, but he does make the case for a dynamic imbalance with equal chances. As always, he writes with clarity and humor even in this rather densely packed work. And although in many cases nothing very clear emerges from the complications, Ward's chapter summaries at least point to the most important games and ideas. This book is recommended for intermediate through advanced players, and is most useful as a theoretical work and not a teaching guide.