^Mallow D, Ludwig D, Nilson G (2003). True Vipers: Natural History and Toxinology of Old World Vipers. Malabar, Florida: Krieger Publishing Company. 359 pp. ISBN0-89464-877-2.
^Steward JW (1971). The Snakes of Europe. Cranbury, New Jersey: Associated University Press (Fairleigh Dickinson University Press). 238 pp. LCCCN 77-163307. ISBN0-8386-1023-4.
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