1. Baumeister, H., Cerioli, M., Haxthausen, A., Mossakowski, T., Mosses, P.D., Sannella, D., Tarlecki, A.: CASL Semantics. In: Mosses, P.D. (ed.) CASL Reference Manual, Part III. LNCS, vol. 2960. Springer, London (2004). Edited by Sannella, D., Tarlecki, A
2. Borceux, F.: Handbook of Categorical Algebra I - III. Cambridge University Press, Cambridge (1994)
3. Căzănescu, V.E., Rosu, G.: Weak inclusion systems. Math. Struct. Comput. Sci. 7(2), 195–206 (1997)
4. Codescu, M., Mossakowski, T.: Heterogeneous colimits. In: Boulanger, F., Gaston, C., Schobbens, P.-Y. (ed.) MoVaH 2008 Workshop. IEEE Press (2008)
5. Diaconescu, R.: Institution-Independent Model Theory. Birkhäuser, Basel (2008)