Sickel W. Some error estimates for periodic interpolation of functions from Besov spaces / W. Sickel, F. Sprengel, 1998. - 18 p. - Текст : непосредственный.
Yuan W. Morrey and campanato meet besov, lizorkin and triebel / W. Yuan, W. Sickel, D. Yang, 2010 r=on-line. - Текст : электронный.