diff --git a/books/free-programming-books-subjects.md b/books/free-programming-books-subjects.md
index f50c9581a..8b4360fcf 100644
--- a/books/free-programming-books-subjects.md
+++ b/books/free-programming-books-subjects.md
@@ -144,7 +144,7 @@ Books that cover a specific programming language can be found in the  [BY PROGRA
 
 * [Bitcoin and Cryptocurrency Technologies](http://bitcoinbook.cs.princeton.edu) - Arvind Narayanan, Joseph Bonneau, Edward Felten, Andrew Miller, Steven Goldfeder, Jeremy Clark (PDF)
 * [Blockchain for Dummies, 2nd IBM Limited Edition](https://www.ibm.com/downloads/cas/36KBMBOG) - Manav Gupta (PDF)
-* [chain.courses](https://chain.courses) - James Gan, Rishub Kumar
+* [chain.courses](https://web.archive.org/web/20220127020549/https://chain.courses/) - James Gan, Rishub Kumar
 * [Getting Started with Enterprise Blockchain: A Guide to Design and Development](https://www.ibm.com/downloads/cas/RYWXAR0M) - Michael Bradley, David Gorman, Matt Lucas, Matthew Golby-Kirk (PDF)
 * [Grokking Bitcoin](https://rosenbaum.se/book/) - Kalle Rosenbaum (HTML)
 * [IBM Blockchain: The Founder’s Handbook, Third Edition](https://www.ibm.com/downloads/cas/GZPPMWM5) - Antonio Banda, Matthew Hamilton, Eileen Lowry, John Widdifield, et al. (PDF)
@@ -363,10 +363,9 @@ Books that cover a specific programming language can be found in the  [BY PROGRA
 * [Bayesian Reasoning and Machine Learning](http://web4.cs.ucl.ac.uk/staff/D.Barber/pmwiki/pmwiki.php?n=Brml.HomePage)
 * [Deep Learning](http://www.deeplearningbook.org) - Ian Goodfellow, Yoshua Bengio, Aaron Courville
 * [Deep Learning for Coders with Fastai and PyTorch](https://github.com/fastai/fastbook) - Jeremy Howard, Sylvain Gugger (Jupyter Notebooks)
-* [Deep Learning with PyTorch](https://pytorch.org/assets/deep-learning/Deep-Learning-with-PyTorch.pdf) - Eli Stevens, Luca Antiga, Thomas Viehmann (PDF)
 * [Dive into Deep Learning](http://d2l.ai)
 * [Explorations in Parallel Distributed Processing: A Handbook of Models, Programs, and Exercises](https://web.stanford.edu/group/pdplab/pdphandbook) - James L. McClelland
-* [Foundations of Machine Learning, Second Edition](https://mitpress.ublish.com/ereader/7093/?preview=#page/Cover) - Mehryar Mohri, Afshin Rostamizadeh, Ameet Talwalkar
+* [Foundations of Machine Learning, Second Edition](https://mitpress.ublish.com/ebook/foundations-of-machine-learning--2-preview/7093/Cover) - Mehryar Mohri, Afshin Rostamizadeh, Ameet Talwalkar
 * [Free and Open Machine Learning](https://nocomplexity.com/documents/fossml/) - Maikel Mardjan (HTML)
 * [Gaussian Processes for Machine Learning](http://www.gaussianprocess.org/gpml/) - Carl Edward Rasmussen, Christopher K.I. Williams
 * [IBM Machine Learning for Dummies](https://www.ibm.com/downloads/cas/GB8ZMQZ3) - Judith Hurwitz, Daniel Kirsch
@@ -675,7 +674,7 @@ Books that cover a specific programming language can be found in the  [BY PROGRA
 ### Parallel Programming
 
 * [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://web.archive.org/web/20170702124132/https://hpc.llnl.gov/training/tutorials) (LLNL materials)
+* [High Performance Computing Training](https://hpc.llnl.gov/documentation/tutorials) (LLNL materials)
 * [High-Performance Scientific Computing](https://andreask.cs.illinois.edu/Teaching/HPCFall2012) (class lectures and slides)
 * [Introduction to High-Performance Scientific Computing](http://pages.tacc.utexas.edu/~eijkhout/istc/istc.html) - Victor Eijkhout
 * [Introduction to Parallel Computing](https://hpc.llnl.gov/documentation/tutorials/introduction-parallel-computing-tutorial) - Blaise Barney