By N. I Muskhelishvili
TO the 1st ENGLISH version. In getting ready this translation, i've got taken the freedom of together with footnotes broadly speaking textual content or putting them in small kind on the acceptable locations. i've got additionally corrected minor misprints with no precise point out .. The Chapters and Sections of the unique textual content were referred to as elements and Chapters respectively, the place the latter were numbered consecutively. the topic index used to be now not inside the Russian unique and the authors' index represents an extension of the unique record of references. during this means the reader might be capable of finding fast the pages on which somebody reference is mentioned. The transliteration challenge has been triumph over by way of printing the names of Russian authors and journals additionally in Russian style. whereas getting ready this translation within the first position for my very own informa tion, the information that it can additionally develop into obtainable to a wide circle of readers has made the trouble doubly beneficial. i believe definite that the reader will proportion with me in my admiration for the simplicity and lucidity of presentation.