Figueiredo, Madeleine Alves de, et al. “Floral and Fruit Characteristics of Blackberry Cultivars, and in Vitro Germination of Their Pollen Grains”. Pesquisa Agropecuaria Brasileira, vol. 48, no. 7, Oct. 2013, pp. 731-40, doi:10.1590/S1678-3921.pab2013.v48.13984.