Arminius and Teutoburger Wald: Short summary of the battle.
Cassius Dio Roman History: Book LVI: Excerpt from the Cary translation provided by LacusCurtius describing the defeat of Varus' legions.
Encyclopædia Britannica: Arminius: Short biography of the military leader. From the 11th edition (1911).
The Teutoburg Massacre AD 9: Account of the massacre of Quinctilius Varus and his three Roman legions by German tribes, with references.
Who Was Arminius?: An account of the Cherusci chief Hermann, called Arminius by the Romans, with related links.
Wikipedia: Arminius: A short biography.