^"military unit." Encyclopædia Britannica. 2010. Encyclopædia Britannica Online. 16 Oct. 2010 <http://www.britannica.com/EBchecked/topic/1346160/military-unit （页面存档备份，存于互联网档案馆）>: "Administratively, several ships of the same type (e.g., destroyers) are organized into a squadron. Several squadrons in turn form a flotilla, several of which in turn form a fleet. For operations, however, many navies organize their vessels into task units (3–5 ships), task or battle groups (4–10 ships), task forces (2–5 task groups), and fleets (several task forces)."