Victor Chepoi Feodor F. Dragan Chenyu Yan Additive sparse spanners for graphs with bounded length of largest induced cycle. 54-75 2005 347 Theor. Comput. Sci. 1-2 http://dx.doi.org/10.1016/j.tcs.2005.05.017 db/journals/tcs/tcs347.html#ChepoiDY05