Trading Space for Time in Undirected s-t Connectivity Andrei Z. Broder Anna R. Karlin Prabhakar Raghavan Eli Upfal 543-549 conf/stoc/STOC21 1989 STOC db/conf/stoc/stoc89.html#BroderKRU89 http://doi.acm.org/10.1145/73007.73059