add references

doku/bib.bib

@@ -1 +1,40 @@
+@article{dbcs1,
+	note = {https://stackoverflow.com/questions/10740293/insert-an-insertion-date-value-into-a-sql-table-automatically},
+	Urldate = {2017-07-24},
+	title = {Insert an {``}insertion date{''} value into a SQL table automatically?},
+	year = {2012},
+    month= {05},
+    day = {24},
+	tags = "db_case-study"
+}
+
+@article{dbcs2,
+	note = {http://excel2latex.com/},
+	Urldate = {2017-07-24},
+	title = {excel => LaTeX},
+	year = {2017},
+    month= {07},
+    day = {24},
+	tags = "db_case-study"
+}
+
+@article{dbcs3,
+	note = {https://tex.stackexchange.com/questions/133/how-can-i-make-a-table-that-takes-up-more-than-a-single-page},
+	Urldate = {2017-07-24},
+	title = {How can I make a table that takes up more than a single page?},
+	year = {2010},
+    month= {07},
+    day = {26},
+	tags = "db_case-study"
+}
+
+@article{dbcs4,
+	note = {http://www.personal.ceu.hu/tex/footnote.htm},
+	Urldate = {2017-07-24},
+	title = {LaTeX Footnotes},
+	year = {2017},
+    month= {07},
+    day = {24},
+	tags = "db_case-study"
+}