diff --git a/free-programming-books.md b/free-programming-books.md
index 0e511d974ab62a8baf06101772e4a8281afb409a..54077df825dbcabe4793fa13ed036de548859be6 100644
--- a/free-programming-books.md
+++ b/free-programming-books.md
@@ -344,7 +344,7 @@
 * [Data Mining Algorithms In R](https://en.wikibooks.org/wiki/Data_Mining_Algorithms_In_R)
 * [Internet Advertising: An Interplay among Advertisers, Online Publishers, Ad Exchanges and Web Users](http://arxiv.org/pdf/1206.1754v2.pdf) (PDF)
 * [Introduction to Data Science](https://docs.google.com/file/d/0B6iefdnF22XQeVZDSkxjZ0Z5VUE/edit?pli=1) - Jeffrey Stanton
-* [Mining of Massive Datasets](http://infolab.stanford.edu/~ullman/mmds.html)
+* [Mining of Massive Datasets](http://www.mmds.org/)
 * [School of Data Handbook](http://schoolofdata.org/handbook/)
 * [Theory and Applications for Advanced Text Mining](http://www.intechopen.com/books/theory-and-applications-for-advanced-text-mining)
 
@@ -387,7 +387,6 @@
 
 * [A First Course in Linear Algebra](http://linear.ups.edu) - Robert A. Beezer
 * [Advanced Algebra](http://www.math.stonybrook.edu/~aknapp/download/a2-alg-inside.pdf) - Anthony W. Knapp (PDF)
-* [An Introduction to Statistics](http://work.thaslwanter.at/Stats/html/) - Thomas Haslwanter (using Python)
 * [Basic Algebra](http://www.math.stonybrook.edu/~aknapp/download/b2-alg-inside.pdf) - Anthony W. Knapp (PDF)
 * [Bayesian Methods for Hackers](https://github.com/CamDavidsonPilon/Probabilistic-Programming-and-Bayesian-Methods-for-Hackers) - Cameron Davidson-Pilon
 * [Calculus Made Easy](http://www.gutenberg.org/ebooks/33283) - Silvanus P. Thompson (PDF)
@@ -528,7 +527,6 @@
 * [The Cathedral and the Bazaar](http://www.catb.org/esr/writings/cathedral-bazaar/) - Eric S. Raymond
 * [The Future of the Internet](http://futureoftheinternet.org)
 * [The Open Source Way](http://www.theopensourceway.org/book/)
-* [The Performance of Open Source Applications](http://aosabook.org/en/)
 * [The Wealth of Networks: How Social Production Transforms Markets and Freedom](http://cyber.law.harvard.edu/wealth_of_networks/Main_Page) - Yochai Benkler
 
 
@@ -553,7 +551,6 @@
 * [High Performance Computing](http://cnx.org/contents/bb821554-7f76-44b1-89e7-8a2a759d1347%405.2) - Charles Severance & Kevin Dowd (PDF, ePUB)
 * [High Performance Computing Training](https://computing.llnl.gov/?set=training&page=index) (LLNL materials)
 * [High-Performance Scientific Computing](http://bit.ly/hpc12) (class lectures and slides)
-* [How to Write Parallel Programs](http://www.lindaspaces.com/book/)
 * [Introduction to High-Performance Scientific Computing](http://pages.tacc.utexas.edu/~eijkhout/istc/istc.html) - Victor Eijkhout
 * [Introduction to Parallel Computing](https://computing.llnl.gov/tutorials/parallel_comp/) - Blaise Barney
 * [Is Parallel Programming Hard, And, If So, What Can You Do About It?](https://www.kernel.org/pub/linux/kernel/people/paulmck/perfbook/perfbook.html) - Paul E. McKenney
@@ -602,7 +599,6 @@
 #### Security
 
 * [Crypto 101 - Crypto for everyone](https://www.crypto101.io)
-* [CryptoParty Handbook](https://www.cryptoparty.in/documentation/handbook)
 * [Handbook of Applied Cryptography](http://cacr.uwaterloo.ca/hac/index.html)
 * [How to deal with Passwords](https://github.com/MHM5000/pass)
 * [Intrusion Detection Systems with Snort](http://ptgmedia.pearsoncmg.com/images/0131407333/downloads/0131407333.pdf) (PDF)
@@ -652,7 +648,6 @@
 * [Introduction to Computing](http://www.computingbook.org)
 * [Introduction to Theory of Computation](http://cglab.ca/~michiel/TheoryOfComputation/) - Anil Maheshwari and Michiel Smid (PDF)
 * [Models of Computation](http://cs.brown.edu/people/jes/book/) - John E. Savage
-* [Network Science](http://barabasilab.neu.edu/networksciencebook/index.html)
 * [Practical Foundations for Programming Languages, Preview](http://www.cs.cmu.edu/~rwh/plbook/book.pdf) - Robert Harper (PDF)
 * [Principles of Programming Languages](https://web.archive.org/web/20150418034451/http://www.cs.jhu.edu/~scott/pl/book/dist/) - Scott F. Smith
 * [Programming and Programming Languages](http://papl.cs.brown.edu/2014/index.html) - Shriram Krishnamurthi