Silva, Gilvaldo Alves da. “Telecommunications Unionism in Paraná: Sinttel’S Strategy in Relation to Sercomtel in the 1980S and 1990S”. Mediações - Revista De Ciências Sociais, vol. 14, no. 2, Nov. 2009, pp. 252-66, doi:10.5433/2176-6665.2009v14n2p252.