CONTENTS INTRODUCTION.................................................................................................................................................................................................... 3 CHAPTER I. Preliminary concepts..................................................................................................................................................................... 6 CHAPTER II. Classes $\bar{ℳ}$, $\bar\mathscr{N}$, $\bar\mathfrak{M}$, $\bar\mathfrak{N}$ and their properties...................... 12 CHAPTER III. The Marcinkiewicz-Orlicz spaces............................................................................................................................................... 44 CHAPTER IV. Generalized almost-periodic functions..................................................................................................................................... 48 REFERENCES......................................................................................................................................................................................................... 64