1. An institution-independent proof of the Beth definability theorem;Aiguier;Stud. Log.,2007
2. Łoś lemma holds in every category;Andréka;Studia Sci. Math. Hung.,1978
3. A general axiomatizability theorem formulated in terms of cone-injective subcategories;Andréka,1981
4. Models and Ultraproducts;Bell,1969
5. Characterization of computable data types by means of a finite equational specification method;Bergstra,1980