-@misc{lambdadeltaV2,
- author="F. {Guidi}",
- title="{lambdadelta\_2}",
- howpublished="Formal specification for the proof assistant Matita 0.99.2",
+@misc{lambdadeltaV2b,
+ author="Ferruccio {Guidi}",
+ title="{lambdadelta\_2B}",
+ howpublished="Formal specification for the interactive prover Matita 0.99.4",
+ year="2019",
+ month="November",
+ note="Available at $\lambda\delta$ Web site: $<$\url{http://lambdadelta.info/}$>$"
+}
+
+@techreport{lambdadeltaR2c,
+ author="Ferruccio {Guidi}",
+ title="{Extending the Applicability Condition in the Formal System $\lambda\delta$}",
+ type="Technical Report",
+ number="AMS Acta 4411",
+ institution="University of Bologna",
+ address="Bologna, Italy",
+ year="2015",
+ month="December",
+ note="CoRR identifier 1411.0154"
+}
+
+@misc{lambdadeltaV2a,
+ author="Ferruccio {Guidi}",
+ title="{lambdadelta\_2A}",
+ howpublished="Formal specification for the interactive prover Matita 0.99.2",