TY  - JOUR
AU  - ​ ​
TI  - Paper has been retracted by the Editors in Chief with author’s permission.
	
JO  - Ars Mathematica Contemporanea
PY  - 2018
SP  - 15
EP  - 23
VL  - 14
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/AMC_2018__14_1_a2/
LA  - en
ID  - AMC_2018__14_1_a2
ER  -