Here we list some papers (in order of appearance) on the topic of GMT somewhat broadly construed.
1. A. Di Nola and G. Gerla. Fuzzy models of first-order languages, Zeitschrift für
Mathematische Logik und Grundlagen der Mathematik 32 (19-24): 331-340 (1986).
2. R. Belohlavek. Model theory for fuzzy logic in the foundations of soft computing, 2000 IEEE International Conference on Systems, Man, and Cybernetics, vol. 5, pp. 3635-3640 (2000).
3. P. Hájek and P. Cintula. On theories and models in fuzzy predicate logics, Journal of Symbolic Logic, 71(3): 863-880 (2006).
4. P. Murinová and V. Novák. Omitting types in fuzzy logic with evaluated syntax, Mathematical Logic Quarterly 52 (3): 259-268 (2006).
5. A. Di Nola, G. Georgescu, and L. Spada. Forcing in Lukasiewicz predicate logic, Studia Logica 89(1):111-145 (2008).
6. P. Cintula, F. Esteva. J. Gispert, L. Godo, F. Montagna and C. Noguera. Distinguished algebraic semantics for t-norm based fuzzy logics: Methods and algebraic equivalences. Annals of Pure and Applied Logic 160: 53-81 (2009).
7. Dellunde, P. y Esteva, F. On elementary extensions in Fuzzy Predicate Logics, Lecture Notes in Artificial Intelligence, Vol. 6178, Dortmund, pp. 747-756 (2010).
8. P. Dellunde. Preserving mappings in fuzzy predicate logics, Journal of Logic and Computation, 22(6): 1367-1389 (2011).
9. P. Dellunde. Revisiting ultraproducts in fuzzy predicate logics, Journal of Multiple-Valued Logic and Soft Computing 19(1):95-108 (2012).
10. P. Dellunde and F. Esteva. On elementary equivalence in fuzzy predicate logics, Archives of Mathematical Logic, 52: 1-17 (2013).
11. X. Caicedo and J. Iovino. Omitting uncountable types and the strength of [0,1]-valued logics, Annals of Pure and Applied Logic, 165: 1169-1200 (2014).
12. P. Dellunde. Applications of ultraproducts: from compactness to fuzzy elementary classes. Logic Journal of the IGPL, 22 (1): 166-180 (2014).
13. P. Cintula and C. Noguera. A Henkin-style proof of completeness for first-order algebraizable logics. Journal of Symbolic Logic 80: 341-358 (2015).
14. V. Costa and P. Dellunde. On Free Models for Horn Classes over Predicate Fuzzy Logics, 18th International Conference of the Catalan Association for Artificial Intelligence (2015).
15. P. Dellunde, A. García-Cerdaña and C. Noguera. Löwenheim-Skolem theorems for non-classical first-order algebraizable logics, Logic Journal of the IGPL , 24 (3): 321-345 (2016).
16. V. Costa and P. Dellunde. On the existence of free models in fuzzy universal Horn classes, Journal of Applied Logic, 23: 3-15 (2017).
17. X. Caicedo. Maximality of continuous logic. In: Beyond first order model theory, Chapman & Hall (2017).
18. V. Costa and P. Dellunde. Term models of Horn clauses over Rational Pavelka Predicate Logic, IEEE International Symposium on multiple-Valued Logic, pp. 112-117 (2017).
19. R. Horcik, T. Moraschini, and A. Vidal. An Algebraic Approach to Valued Constraint Satisfaction, in Valentin Goranko and Mads Dam (editors), 26th EACSL Annual Conference on Computer Science Logic (CSL 2017), Leibniz International Proceedings in Informatics, vol. 82, pp 1-20, Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik, Dagstuhl, Germany, (2018).
20. P. Dellunde, A. García-Cerdaña and C. Noguera. Back-and-forth systems for first order fuzzy logics, Fuzzy Sets and Systems, to appear.
21. G. Badia and C. Noguera. Saturated models in mathematical fuzzy logic, Proceedings of the IEEE ISMVL 2018, to appear.
22. G. Badia and C. Noguera. Fraisse classes of graded relational structures, Theoretical Computer Science, to appear.
23. G. Badia, V. Costa, P. Dellunde and C. Noguera. Syntactic characterizations of classes of first order structures in mathematical fuzzy logic, submitted.
24. P. Cintula and D. Diaconescu. Omitting Types Theorem for Fuzzy Logics, submitted.