 Topics related to non-extensionality, in particular modal logics and Kripkean semantics, were also treated by some philosophers of logic in Latin America (e.g., Mortari 2007; Marcos 2009; Estrada González 2012; Rosenblatt and Szmuc 2014). In particular, Max Freund (2001, 2004, 2007, 2015) focused on modal logics with sortal quantifiers and wrote a collaborative book on modal logic (Cocchiarella and Freund 2008).