W. S. Siegen and K. Z. Tubingen.International Symposium on Multivariate Approximation theory(3rd : 1982 : Black Forest)：Multivariate approximation theory II; proceedings of the conference．V.2.Birkhauser Verlag,1982.
International Symposium on Multivariate Approximation theory(3rd : 1982 : Black Forest)：Multivariate approximation theory II; proceedings of the conference．V.2
W. S. Siegen and K. Z. Tubingen.Birkhauser Verlag,1982.
