Union Membership Density and Wages: The Role of Worker, Firm, and Job-Title Heterogeneity
John Addison, Pedro Portugal, Hugo Vilares
Journal of Econometrics, vol. 233, 2023, p. 612-632.

Unions and Collective Bargaining in the Wake of the Great Recession: Evidence from Portugal
John Addison, Pedro Portugal, Hugo Vilares
British Journal Of Industrial Relations, vol. 55, 2017, p. 551-576.