Alexander B. Romanovsky Iain Smith Dependable On-Line Upgrading of Distributed Systems. 975-976 2002 conf/compsac/2002 COMPSAC http://doi.ieeecomputersociety.org/10.1109/CMPSAC.2002.1045132 db/conf/compsac/compsac2002.html#RomanovskyS02