Stuart Rance and Ashley Hanna (30 May 2007). "Glossary of Terms, Definitions and Acronyms"(PDF). ITIL - IT Service Management. Office of Government Commerce. Retrieved 3 June 2012.
Stuart Rance and Ashley Hanna (30 May 2007). "Glossary of Terms, Definitions and Acronyms"(PDF). ITIL - IT Service Management. Office of Government Commerce. Archived from the original(PDF) on 4 April 2012. Retrieved 3 June 2012.
Stuart Rance and Ashley Hanna (30 May 2007). "Glossary of Terms, Definitions and Acronyms"(PDF). ITIL - IT Service Management. Office of Government Commerce. Archived from the original(PDF) on 4 April 2012. Retrieved 3 June 2012.