%0 Conference Paper %A Dahmen, Wolfgang %T Trigonometric approximation with exponential error orders. III. Criteria for asymptotically optimal processes %C Gdansk %M RWTH-CONV-196267 %D 1979 %< Proc. of the International Conference on Approximation and Function Spaces, ed. by Z. Ciesielski %F PUB:(DE-HGF)8 %9 Contribution to a conference proceedings %U https://publications.rwth-aachen.de/record/125825