%0 Journal Article
%A ​ ​
%T Paper has been retracted by the Editors in Chief with author’s permission.
	
%J Ars Mathematica Contemporanea
%D 2018
%P 15-23
%V 14
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/AMC_2018__14_1_a2/
%G en
%F AMC_2018__14_1_a2