diff --git a/books/free-programming-books-langs.md b/books/free-programming-books-langs.md
index 974794c81..9dbc3fb29 100644
--- a/books/free-programming-books-langs.md
+++ b/books/free-programming-books-langs.md
@@ -1421,31 +1421,31 @@ Books on general-purpose programming that don't focus on a specific language are
 ### Jenkins
 
 * [Jenkins Starter Guide Ebook](https://bugfender.com/wp-content/themes/bugfender-wordpress-theme/assets/docs/Jenkins-Starter-Guide-Ebook.pdf) (PDF)
-* [Jenkins: The Definitive Guide](http://www.bogotobogo.com/DevOps/Jenkins/images/Intro_install/jenkins-the-definitive-guide.pdf) (PDF)
+* [Jenkins: The Definitive Guide](http://www.bogotobogo.com/DevOps/Jenkins/images/Intro_install/jenkins-the-definitive-guide.pdf) (PDF) (CC BY-NC-ND)
 * [Jenkins User Handbook](https://www.jenkins.io/user-handbook.pdf) (PDF)
-* [Learning Jenkins](https://riptutorial.com/Download/jenkins.pdf) Compiled from StackOverflow Documentation (PDF)
+* [Learning Jenkins](https://riptutorial.com/Download/jenkins.pdf) Compiled from StackOverflow Documentation (PDF) (CC BY-SA)
 
 
 ### Julia
 
-* [Introducing Julia](https://en.wikibooks.org/wiki/Introducing_Julia) - Wikibooks
+* [Introducing Julia](https://en.wikibooks.org/wiki/Introducing_Julia) - Wikibooks (CC BY-SA)
 * [Julia by Example](http://samuelcolvin.github.io/JuliaByExample) - Samuel Colvin (GitHub repo)
-* [Julia Data Science](https://juliadatascience.io) - Jose Storopoli, Rik Huijzer, Lazaro Alonso
+* [Julia Data Science](https://juliadatascience.io) - Jose Storopoli, Rik Huijzer, Lazaro Alonso (CC BY-NC-SA)
 * [Julia language: a concise tutorial](https://syl1.gitbook.io/julia-language-a-concise-tutorial) - Antonello Lobianco (GitBook)
-* [Learn Julia in Y minutes](https://learnxinyminutes.com/docs/julia) - Leah Hanson
-* [Quantitative Economics with Julia](https://julia.quantecon.org) - Jesse Perla, Thomas J. Sargent, John Stachurski (HTML, [PDF](https://web.archive.org/web/20210713122108/https://julia.quantecon.org/_downloads/pdf/quantitative_economics_with_julia.pdf)) *(:card_file_box: archived)*
+* [Learn Julia in Y minutes](https://learnxinyminutes.com/docs/julia) - Leah Hanson (CC BY-SA)
+* [Quantitative Economics with Julia](https://julia.quantecon.org) - Jesse Perla, Thomas J. Sargent, John Stachurski (HTML, [PDF](https://web.archive.org/web/20210713122108/https://julia.quantecon.org/_downloads/pdf/quantitative_economics_with_julia.pdf)) *(:card_file_box: archived)* (CC BY-SA)
 * [The Julia Express](http://bogumilkaminski.pl/files/julia_express.pdf) - Bogumił Kamiński (PDF)
-* [Think Julia](https://benlauwens.github.io/ThinkJulia.jl/latest/book.html) - Ben Lauwens, Allen Downey (GitBook)
+* [Think Julia](https://benlauwens.github.io/ThinkJulia.jl/latest/book.html) - Ben Lauwens, Allen Downey (GitBook) (CC BY-NC)
 
 
 ### Kotlin
 
-* [Essential Kotlin](https://www.programming-books.io/essential/kotlin/) - Krzysztof Kowalczyk, StackOverflow Contributors
-* [Kotlin Notes for Professionals](https://goalkicker.com/KotlinBook/) - Compiled from StackOverflow documentation (PDF)
+* [Essential Kotlin](https://www.programming-books.io/essential/kotlin/) - Krzysztof Kowalczyk, StackOverflow Contributors (CC BY-SA)
+* [Kotlin Notes for Professionals](https://goalkicker.com/KotlinBook/) - Compiled from StackOverflow documentation (PDF) (CC BY-SA)
 * [Kotlin Official Documentation](https://kotlinlang.org/docs/reference/)
-* [Kotlin Quick Reference](https://kotlin-quick-reference.com) - Alvin Alexander (gitbook)
+* [Kotlin Quick Reference](https://kotlin-quick-reference.com) - Alvin Alexander (gitbook) (CC BY-SA)
 * [Learn Kotlin Programming](https://www.programiz.com/kotlin-programming) - Programiz
-* [Learning Kotlin](https://riptutorial.com/Download/kotlin.pdf) - Compiled from StackOverflow Documentation (PDF)
+* [Learning Kotlin](https://riptutorial.com/Download/kotlin.pdf) - Compiled from StackOverflow Documentation (PDF) (CC BY-SA)
 
 
 ### LaTeX / TeX