diff --git a/Koli_2017/Koli_2017_Stanger.bib b/Koli_2017/Koli_2017_Stanger.bib
index f17d307..804a489 100644
--- a/Koli_2017/Koli_2017_Stanger.bib
+++ b/Koli_2017/Koli_2017_Stanger.bib
@@ -144,6 +144,17 @@
 	Isbn = {978-1-60558-233-7},
 	Title = {Multi-{RQP}: {G}enerating test databases for the functional testing of {OLTP} applications}}
 
+@article{Brusilovsky.P-2010a-Learning,
+	Articleno = {19},
+	Author = {Peter  Brusilovsky and Sergey Sosnovsky and Michael V. Yudelson and Danielle H. Lee and Vladimir Zadorozhny and Xin Zhou},
+	Doi = {10.1145.1656255.1656257},
+	Journal = {ACM Transactions on Computing Education},
+	Month = jan,
+	Number = {4},
+	Title = {Learning {SQL} programming with interactive tools: {F}rom integration to personalization},
+	Volume = {9},
+	Year = {2010}}
+
 @book{Cattell.R-2000a-ODMG3,
 	Address = {San Francisco, California, USA},
 	Author = {R. G. G. Cattell and Douglas K. Barry and Mark Berler and Jeff Eastman and David Jordan and Craig Russell and Olaf Schadow and Torsten Stanienda and Fernando Velez},
@@ -202,6 +213,16 @@
 	Url = {http://dl.acm.org/citation.cfm?id=1273730.1273737},
 	Title = {Computer assisted assessment of SQL query skills}}
 
+@article{Dietrich.S-1993a-An-educational,
+	Author = {Suzanne W. Dietrich},
+	Doi = {10.1080/0899340930040201},
+	Journal = {Computer Science Education},
+	Number = {2},
+	Pages = {157--184},
+	Title = {An educational tool for formal relational database query languages},
+	Volume = {4},
+	Year = {1993}}
+
 @inproceedings{Dietrich.S-1997a-WinRDBI,
 	Author = {Suzanne W. Dietrich and Eric Eckert and Kevin Piscator},
 	Crossref = {Lewis.J-1998a-SIGCSE},
@@ -276,6 +297,25 @@
 	Pages = {307--311},
 	Title = {Learning {SQL} with a computerized tutor}}
 
+@article{Ohlsson.S-1992a-Constraint-based,
+	Author = {Stellan Ohlsson},
+	Journal = {Journal of Artificial Intelligence in Education},
+	Number = {4},
+	Pages = {429--447},
+	Title = {Constraint-based student modelling},
+	Volume = {3},
+	Year = {1992}}
+
+@article{Ohlsson.S-2016a-Constraint-based,
+	Author = {Stellan Ohlsson},
+	Doi = {10.1007/s40593-015-0075-7},
+	Journal = {International Journal of Artificial Intelligence in Education},
+	Number = {1},
+	Pages = {457--473},
+	Title = {Constraint-based modeling: {F}rom cognitive theory to computer tutoring -- and back again},
+	Volume = {26},
+	Year = {2016}}
+
 @inproceedings{Prior.J-2004a-Backwash,
 	Author = {Julia Coleman Prior and Raymond Lister},
 	Crossref = {Boyle.R-2004a-ITiCSE},