TY  - JOUR
AU  - E.S. Freidkin
AU  - S.A. Freidkin
TI  - On a problem by Shapiro.
JO  - Elemente der Mathematik
PY  - 1990
SP  - 137
EP  - 139
VL  - 45
IS  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/ELMA_1990__45_6_141491/
ID  - ELMA_1990__45_6_141491
ER  -