Get the Whitepaper called SFX-SQLi – Fast data extraction using SQL injection and XML statements.
You can download it from the following link: https://packetstormsecurity.com/files/download/74740/SFX-SQLi-Paper-en.pdf
Source: https://packetstormsecurity.com/files/74740/SFX-SQLi-Select-For-XML-SQL-Injection.html