found: Klein, A.G. Common adders, 2005:CIP galley (European adders or Common adders)
found: ITIS WWW site, Mar. 3, 2005(Vipera berus)
found: Index to organism names WWW site, Mar. 4, 2005(Vipera berus)
found: Mehrtens, J.M. Living snakes of the world, 1987:p. 331 (Adder; crossed viper; Kreuzotter; Vipera berus berus)
found: Coborn, J. Atlas of snakes of the world, 1991:p. 496 (Vipera berus; adder or northern viper)
found: Snake species of the world, 1999:v. 1, p. 397 (Vipera berus)
found: Web. 3(adder: 1) the common viper (Vipera berus) of Europe, or, any other snake of family Viperidae; 2) puff adder; 3) krait; 4) any of several families of harmless No. Am. snakes)
found: Random House(adder: 1) the common European viper (Vipera berus); 2) any of various other venomous or harmless snakes resembling the viper)
