Andrei Z. Broder Anna R. Karlin Prabhakar Raghavan Eli Upfal Trading Space for Time in Undirected s-t Connectivity. 324-334 1994 23 SIAM J. Comput. 2 db/journals/siamcomp/siamcomp23.html#BroderKRU94 http://dx.doi.org/10.1137/S0097539790190144