Refine and clarify the content

docs/thesis/ref.bib

@@ -902,3 +902,18 @@ numpages = {3}
   year={2020},
   publisher={MIT Press One Rogers Street, Cambridge, MA 02142-1209, USA journals}
 }
+
+@book{russell2010artificial,
+  title={Artificial intelligence a modern approach},
+  author={Russell, Stuart J},
+  year={2010},
+  publisher={Pearson Education, Inc.}
+}
+
+@book{momjian2001postgresql,
+  title={PostgreSQL: introduction and concepts},
+  author={Momjian, Bruce},
+  volume={192},
+  year={2001},
+  publisher={Addison-Wesley New York}
+}