Endogenous Fluctuations in Unionized Economies with Productive Externalities
Rui Coimbra, Teresa Lloyd-Braga, Leonor Modesto
Economic Theory, vol. 26, 2005, p. 629-649.

Efficient Union Contracts in the Presence of Homogeneous Labor and Differentiated Unions
Ana Paula Martins, Rui Coimbra
Annals of Economics and Finance, vol. 5, 2004, p. 27-46.