Simultaneous approximation of periodic functions and their derivatives by fourier sums
1982 ◽
Vol 33
(3)
◽
pp. 274-282
◽
1986 ◽
Vol 38
(2)
◽
pp. 180-185
◽
1989 ◽
Vol 41
(2)
◽
pp. 189-199
◽