Brandão, Paulo Eduardo, et al. “The Cap Gene of Porcine Circovirus Type 2 (PCV2) Evolves by Positive Selection in Vitro”. Brazilian Journal of Veterinary Research and Animal Science, vol. 47, no. 3, June 2010, pp. 208-11, https://doi.org/10.11606/issn.1678-4456.bjvras.2010.26857.