FONSECA, Filomena, et al. “Genetic Variants of Grapevine Leafroll-Associated Virus 2 Infecting Portuguese Grapevine Cultivars”. Phytopathologia Mediterranea, vol. 55, no. 1, May 2016, pp. 73-88, doi:10.14601/Phytopathol_Mediterr-16378.