diff --git a/_posts/16-10-01-Books.md b/_posts/16-10-01-Books.md
index 6ad76a6..6277ddc 100644
--- a/_posts/16-10-01-Books.md
+++ b/_posts/16-10-01-Books.md
@@ -15,6 +15,8 @@ book to be added, send a PR and it will be reviewed for relevancy.
 ### Free Books
 
 * [PHP The Right Way](https://leanpub.com/phptherightway/) - This website is available as a book completely for free.
+* [Using Libsodium in PHP Projects](https://paragonie.com/book/pecl-libsodium) - Guide to using Libsodium PHP extension
+for modern, secure, and fast cryptography.
 
 ### Paid Books