Alexander I. Stepanets 
Uniform Approximations by Trigonometric Polynomials [PDF ebook] 

Frontmatter — Contents — Preface to the English Edition — Preface to the Russian Edition — Introduction — Chapter 1. SIMPLEST EXTREMAL PROBLEMS — Chapter 2. APPROXIMATION OF FUNCTIONS OF ONE VARIABLE BY FOURIER SUMS — Chapter 3. APPROXIMATION OF FUNCTIONS OF MANY VARIABLES BY FOURIER SUMS — Chapter 4. FEJER SUMS — Chapter 5. SPHERICAL RIESZ SUMS — Chapter 6. ROGOSINSKI SUMS — Chapter 7. FAVARD SUMS — REFERENCES — SUBJECT INDEX