diff --git a/free-courses-en.md b/free-courses-en.md
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 * [Ruby](#ruby)
 
 ###Databases
-* [Introduction to Databases](https://class.stanford.edu/courses/Engineering/db/2014_1/about) (Stanford Univesity)
+* [Database Systems](http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-830-database-systems-fall-2010/) (MIT's opencourseware)
+* [Introduction to Databases](https://class.stanford.edu/courses/Engineering/db/2014_1/about) (Stanford University)
 
 ###HTML / CSS
 * [Code a personal splash page in 1 hour: A Hands-on Intro to HTML & CSS](http://www.thefirehoseproject.com/lessons/splash-page)
diff --git a/free-programming-books.md b/free-programming-books.md
index 22d35aa8f64bea8dfd469d8b98770b531760b43b..6ad67d4ae2536919764455575fadf95af72b9299 100644
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 * [The Art of Computer Programming](http://www.cs.utsa.edu/~wagner/knuth/) (fascicles, mostly volume 4) - Donald Knuth
 * [The Design of Approximation Algorithms](http://www.designofapproxalgs.com/book.pdf) (PDF)
 * [The Great Tree List Recursion Problem](http://cslibrary.stanford.edu/109/TreeListRecursion.pdf) (PDF)
+* [Think Complexity](http://greenteapress.com/complexity/) (PDF)
 
 
 ####Cellular Automata