Fry (February 2006). "Early evolution of the venom system in lizards and snakes". Nature. 439 (7076): 584-588. doi:10.1038/nature04328. PMID16292255.
Delfino, Massimo; Rage, Jean-Claude; Bolet, Arnau; Alba, David M. (2013). "Early Miocene dispersal of the lizard Varanus into Europe:Reassessment of vertebral material from Spain". Acta Palaeontologica Polonica. 58 (4): 731-735. doi:10.4202/app.2012.0025.