Cowley & Parker 2001, p. 511. Cowley, Robert; Parker, Geoffrey (2001). The Reader's Companion to Military History (illustrated ed.). Houghton Mifflin Harcourt. p. 511. ISBN0-618-12742-9.
S., Wells, Peter (2003). The battle that stopped Rome : Emperor Augustus, Arminius, and the slaughter of the legions in the Teutoburg Forest (1st ed.). New York: W.W. Norton. ISBN0393020282. OCLC52251165.{{cite book}}: CS1 maint: multiple names: authors list (link)