Risk assessment as a tool for improving external biosecurity at farm level.Published in:BMC Veterinary Research, 2015, v. 11, n. 1, p. 1, doi. 10.1186/s12917-015-0477-7By:Lewerin, Susanna Sternberg;Österberg, Julia;Alenius, Stefan;Elvander, Marianne;Fellström, Claes;Tråvén, Madeleine;Wallgren, Per;Waller, Karin Persson;Jacobson, MagdalenaPublication type:Article