W. Ramírez-Benavides, J. Monge-Nájera, and J. B. Chavarría, “Sex ratio in two species of Pegoscapus wasps (Hymenoptera: Agaonidae) that develop in figs: can wasps do mathematics, or play sex ratio games?”, Rev. Biol. Trop., vol. 57, no. 3, p. 605−621, Sep. 2009.