Variations in growth and virulence of Leptographium wingfieldii Morelet, a fungus associated with the bark beetle Tomicus piniperda L. François Lieutier, Annie Yart, Hui Ye, Daniel Sauvard and Valérie Gallois Ann. For. Sci., 61 1 (2004) 45-53 DOI: 10.1051/forest:2003083