Myskin K. Yu.
Some Problems of Simultaneous Approximation of Functions of Two Variables and Their Derivatives by Interpolation Bilinear Splines
Ukr. Mat. Zh. - 2005. - 57, № 2. - pp. 147–157
Exact estimates for the errors of approximation of functions of two variables and their derivatives by interpolation bilinear splines are obtained on certain classes.