This collection of examples of the application of quantum chemical methods in the study of various chemical problems (main ly in organic chemistry) arose from an arrangement of the ma terials used by the first of the authors in his lectures on organic quantum chemistry and chemical constitution, delivered since 1959 at the Science Department of the Charles University, as well as in courses of quantum chemistry and, finally, in his lectures on the fundamentals of quantum chemistry held in the years 1965-1967 at the universities of Wiirzburg, Groningen, and Giessen, and at the Technical...