diff --git a/books/free-programming-books-langs.md b/books/free-programming-books-langs.md
index fb4ac00b1..20500cc43 100644
--- a/books/free-programming-books-langs.md
+++ b/books/free-programming-books-langs.md
@@ -997,6 +997,7 @@ Books on general-purpose programming that don't focus on a specific language are
 * [Upgrade Your HTML](https://github.com/frontenddogma/upgrade-your-html) – Jens Oliver Meiert
 * [W3.CSS Succinctly](https://www.syncfusion.com/ebooks/w3_css_succinctly) - Joseph D. Booth
 * [Web Audio API](http://chimera.labs.oreilly.com/books/1234000001552) - Boris Smus
+* [Web Development Essentials](https://learning.lpi.org/en/learning-materials/030-100/) - by Linux Professional Institute (PDF)
 * [Web Visual Effects with CSS3](https://leanpub.com/web-visual-effects-with-css3/read) - Thomas Mak
 
 
@@ -1506,7 +1507,7 @@ Books on general-purpose programming that don't focus on a specific language are
 * [Linux Appliance Design: A Hands-On Guide to Building Linux Appliances](http://librta.org/book.html) - Bob Smith, John Hardin, Graham Phillips, Bill Pierce (PDF, EPUB, MOBI)
 * [Linux commands Notes for Professionals](https://goalkicker.com/LinuxBook/) - Compiled from StackOverflow documentation (PDF)
 * [Linux Device Drivers, Third Edition](http://lwn.net/Kernel/LDD3/) - Jonathan Corbet, Alessandro Rubini, Greg Kroah-Hartman
-* [Linux Essentials - Version: 1.6](https://learning.lpi.org/en/learning-materials/010-160/) - Linux Professional Institute (PDF)
+* [Linux Essentials](https://learning.lpi.org/en/learning-materials/010-160/) - Linux Professional Institute (PDF)
 * [Linux From Scratch](https://www.linuxfromscratch.org/lfs/view/stable/) - Gerard Beekmans, Bruce Dubbs, Ken Moffat, Pierre Labastie, et al.
 * [Linux Fundamentals](http://linux-training.be/linuxfun.pdf) - Paul Cobbaut (PDF)
 * [Linux Inside](https://0xax.gitbooks.io/linux-insides/content/index.html)
diff --git a/books/free-programming-books-subjects.md b/books/free-programming-books-subjects.md
index 09b3ff8c7..b9b386608 100644
--- a/books/free-programming-books-subjects.md
+++ b/books/free-programming-books-subjects.md
@@ -761,6 +761,7 @@ Books that cover a specific programming language can be found in the [BY PROGRAM
 * [Innovation Happens Elsewhere](https://dreamsongs.com/IHE/IHE.html) - Ron Goldman, Richard P. Gabriel
 * [Introduction to Networking](https://do1.dr-chuck.net/net-intro/EN_us/net-intro.pdf) - Charles Severance (PDF)
 * [Open Advice: FOSS: What We Wish We Had Known When We Started](http://open-advice.org)
+* [Open Source Essentials](https://learning.lpi.org/en/learning-materials/050-100/) - by Linux Professional Institute (PDF)
 * [Open source in Brazil](https://www.oreilly.com/ideas/open-source-in-brazil) - Andy Oram
 * [Producing Open Source Software](https://producingoss.com) - Karl Fogel
 * [Roads and Bridges: The Unseen Labor Behind Our Digital Infrastructure](https://www.fordfoundation.org/work/learning/research-reports/roads-and-bridges-the-unseen-labor-behind-our-digital-infrastructure/) - Nadia Eghbal
@@ -929,6 +930,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Practical Cryptography for Developer](https://cryptobook.nakov.com) - Svetlin Nakov (GitBook) ( :construction: *in process*)
 * [Programming Differential Privacy](https://programming-dp.com) - Joseph Near, Chiké Abuah (HTML, PDF)
 * [Security Engineering](https://www.cl.cam.ac.uk/~rja14/book.html)
+* [Security Essentials](https://learning.lpi.org/en/learning-materials/020-100/) -  by Linux Professional Institute (PDF)
 * [The Joy of Cryptography (2021)](https://joyofcryptography.com/pdf/book.pdf) - Mike Rosulek (PDF)
 * [The MoonMath Manual to zk-SNARKs](https://leastauthority.com/community-matters/moonmath-manual/) - Least Authority
 * [The SELINUX Coloring Book](https://github.com/mairin/selinux-coloring-book) -  Daniel J Walsh, Máirín Duffy (PDF) (CC BY-SA)