Analytical solutions to the orbital motion of celestial objects have been nowadays mostly replaced by numerical solutions, but they are still irreplaceable whenever speed is to be preferred to accuracy, or to simplify a dynamical model. In this book, the most common orbital perturbations problems are discussed according to the Lie transforms method, which is the de facto standard in analytical orbital motion calculations. Due to an oversight, an error slipped in Section 4.1 of the book, where it is implicitly assumed the case of the Kepler problem. The following text should replace Sections 4.1 and 4.2 of the book. Cross-references may be affected with the new writing. In particular, former crossed references to Eq.(4.3) should now point to current Eq.(4.12). Please find the Erratum below.