Vasconcelos, Kelly Samá Lopes de, and Monaliza de Oliveira Ferreira. 2014. “Production Specialization and Structural Change in Agriculture of the Northeast Region of Brazil (1990–2011)”. Revista de Política Agrícola 23 (2): 5-19. https://rpa.sede.embrapa.br/RPA/article/view/917.