SQLZOO

• http://sqlzoo.net/wiki/SELECT_basics?answer=1
• http://sqlzoo.net/wiki/SELECT_from_WORLD_Tutorial?answer=1
• http://developer.mimer.com/documentation/html_92/Mimer_SQL_Engine_DocSet/Mimer_SQL_Engine.htm
• http://dev.mysql.com/doc/refman/5.1/en/select.html
• http://docs.oracle.com/cd/B28359_01/server.111/b28286/toc.htm
• http://msdn.microsoft.com/en-us/library/ms189826%28v=sql.90%29.aspx
• http://office.microsoft.com/en-us/assistance/CH062526881033.aspx
• http://pic.dhe.ibm.com/infocenter/db2luw/v9r7/index.jsp
• http://sybooks.sybase.com/sybooks/sybooks.xhtml
• http://www.postgresql.org/docs/current/static/index.html
• http://www.sqlite.org/lang.html
• https://sqlzoo.net/w/index.php?title=SQL_Tutorial&oldid=39523