1. A. N. Kolmogorov and V. M. Tikhomirov, ??-entropy and ?-capacity of sets in function spaces,? Usp. Matem. Nauk,14, No. 2, 3?86 (1959).
2. R. Dudley, ?Metric entropy of some classes of sets with differential boundaries,? J. Approximat. Theory,10, No. 3, 227?236 (1974).
3. A. D. Aleksandrov, Internal Geometry of Convex Surfaces [in Russian], Gostekhizdat, Moscow-Leningrad (1948).
4. S. G. Mikhlin, Course of Mathematical Physics [in Russian], Nauka, Moscow (1968).