@Techreport{Beal98rot,
author = {Marie-Pierre B{\'e}al},
title = {On rotationally invariant codes},
institution = {Institut Gaspard-Monge},
year = 1998,
number = {98-13},
url={http://www-igm.univ-mlv.fr/~beal/Recherche/Publications/rotation.pdf}
}