Periodic Boehmians. Nemzer, Dennis (1989) International Journal of Mathematics and Mathematical Sciences
Permitted trigonometric thin sets and infinite combinatorics Miroslav Repický (2001) Commentationes Mathematicae Universitatis Carolinae We investigate properties of permitted trigonometric thin sets and construct uncountable permitted sets under some set-theoretical assumptions.
Pointwise very strong approximation as a generalization of Fejér's summation theorem. Łenski, Włodzimierz (2005) Annales Mathematicae et Informaticae