In this book the ordinary double enumeration of theorems and formulas separately for each chapter is used. When referring (in a given chapter) to
theorems, subsections, or formulas appearing in another chapter, the number of this chapter is indicated first. When a reference to a theorem and a formula presented in Appendices I or II is given, the triple enumeration is used; for example, (1.A.12) indicates a reference to formula 12 in Appendix I.