http://www.oracle-base.com/articles/10g/automatic-workload-repository-10g.php

http://www.datadisk.co.uk/html_docs/oracle/awr.htm 
http://www.datadisk.co.uk/html_docs/oracle/addm.htm

http://www.oracle.com/technetwork/database/performance/tips-perf-awr-sql-report-129542.pdf

http://www.dba-oracle.com/oracle10g_tuning/t_generating_awr_report.htm
http://www.remote-dba.net/oracle_10g_tuning/t_reading_awr_report_sections.htm