• A. Vos et al. (trans), John Duns Scotus: Contingency and Freedom. Lectura I, 39 (Dordrecht: 1994).

• R. Cross, Duns Scotus on God (Aldershot: 2005).

• S. Knuuttila, Modalities in Medieval Philosophy (London: 1993).

• G. Pini, “Scotus on the Possibility of a Better World,” Acta Philosophica 18 (2009), 283–306.

• M. Sylwanowicz, Contingent Causality and the Foundations of Duns Scotus’ Metaphysics (Leiden: 1996).

• W.A. Frank, “Duns Scotus’ Concept of Willing Freely,” Franciscan Studies 42 (1982), 68-89.

• A.B. Wolter, “Scotus on the Divine Origin of Possibility,” American Catholic Philosophical Quarterly 47 (1993), 95-107.