March 2008
10.1371/journal.pmed.0050062
10.1371/journal.pmed.0050054
10.1371/journal.pmed.0050052
10.1371/journal.pmed.0050041
10.1371/journal.pmed.0050007
10.1371/journal.pmed.0050006
10.1371/journal.pmed.0050067
10.1371/journal.pmed.0050065
10.1371/journal.pmed.0050063
10.1371/journal.pmed.0050053
10.1371/journal.pmed.0050051
10.1371/journal.pmed.0050033
10.1371/journal.pmed.0050069
10.1371/journal.pmed.0050068
10.1371/journal.pmed.0050060
10.1371/journal.pmed.0050056
10.1371/journal.pmed.0050050
10.1371/journal.pmed.0050077
10.1371/journal.pmed.0050074
10.1371/journal.pmed.0050073
10.1371/journal.pmed.0050072
10.1371/journal.pmed.0050071
10.1371/journal.pmed.0050070
10.1371/journal.pmed.0050064
10.1371/journal.pmed.0050082
10.1371/journal.pmed.0050081
10.1371/journal.pmed.0050079
10.1371/journal.pmed.0050076
10.1371/journal.pmed.0050075
10.1371/journal.pmed.0050061
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CLOCKSS system has permission to ingest, preserve, and serve this open access Archival Unit.