Xu X. et al 2004. Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids. Nature431 (7009): 680–684. [1]Archived 2012-04-02 at the Wayback Machine
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Xu X. et al 2004. Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids. Nature431 (7009): 680–684. [1]Archived 2012-04-02 at the Wayback Machine