HUILAN LI, TRUEMAN MACHENRY, THE CONVOLUTION RING OF ARITHMETIC FUNCTIONS AND SYMMETRIC POLYNOMIALS, The Rocky Mountain Journal of Mathematics, Vol. 43, No. 4 (2013), pp. 1227-1259 ...

Todd Dupont, Ridgway Scott, Polynomial Approximation of Functions in Sobolev Spaces, Mathematics of Computation, Vol. 34, No. 150 (Apr., 1980), pp. 441-463 ...