Bernd Bandemer Abbas El Gamal Gonzalo Vazquez-Vilar On the sum capacity of a class of cyclically symmetric deterministic interference channels. 2622-2626 2009 ISIT http://doi.ieeecomputersociety.org/10.1109/ISIT.2009.5205951 conf/isit/2009 db/conf/isit/isit2009.html#BandemerGV09