Mario G. Losano, Accademia delle Scienze di Torino, has published Kelsen's Theory on International Law During His Exile in Geneva at 28 Ratio Juris 470 (2015). Here is the abstract.
Kelsen's monistic theory of international law was shaped during his exile in Geneva (1933–1940), but its deep roots are to be found in his Pure Theory of Law, centred on the neo‐Kantian notion of “system.” According to this conception, a legal system can only descend from a single principle. Consequently, Kelsen constructed a monistic theory of law, i.e., a legal system incorporating all norms into a pyramidal structure culminating in a single principle: the fundamental norm. This Kelsenian pyramid must also include international law, considering that if international law were a legal system different from national law (as the dualistic theory assumes), the theoretical construction would need two fundamental norms. This dualism is as incompatible with Kelsen's monistic vision as Schmitt's theory of “Great Spaces,” creating a hierarchical system of international relations. In the Kelsenian pyramid, international law occupies a position superior to national law: The consequences of this assumption are discussed in some documents recently published in German and French.The full text is not available from SSSRN.