Strong Inapproximability of the Basic <i>k</i>-Spanner Problem.

Michael Elkin David Peleg Strong Inapproximability of the Basic <i>k</i>-Spanner Problem. 636-647 http://dx.doi.org/10.1007/3-540-45022-X_54 2000 conf/icalp/2000 ICALP db/conf/icalp/icalp2000.html#ElkinP00