Brian F. Cooper Arturo Crespo Hector Garcia-Molina Implementing a Reliable Digital Object Archive. 128-143 2000 conf/ercimdl/2000 ECDL http://link.springer.de/link/service/series/0558/bibs/1923/19230128.htm db/conf/ercimdl/ecdl2000.html#CooperCG00