From the reviews: “This book is based on a series of papers which the author published earlier. The main subject of this book is the concept of non-smooth time transformations (NSTT) to describe periodic solutions of essentially nonlinear differential equations. … This book is suitable for scientists interested in applied mathematics, in particular those interested in constructing (approximations of) ... Read moreperiodic solutions for differential equations.” (Wim T. van Horssen, Mathematical Reviews, Issue 2012 j) “The content of this book is built on a new physical idea that the effectiveness of linear and weakly nonlinear dynamic theories is due to the spatio-temporal nature of harmonic motions associated with subgroup of rigid-body rotations. … this original book will be of interest to the experts, professors and post-graduate students in various areas of nonlinear physics, fundamental and engineering mechanics, applied mathematics, and other fields of research dealing with nonlinear dynamic models, non-smooth or discontinuous processes.” (Anatoly Martynyuk, Zentralblatt MATH, Vol. 1202, 2011) Show Less