diff --git a/free-programming-books.md b/free-programming-books.md
index 555cd6bac71b944bf3b4e0b4c1a67a0da0d93b2d..04e6fda2889e103fe630bb55bb586d3d17cbf0f2 100644
--- a/free-programming-books.md
+++ b/free-programming-books.md
@@ -948,6 +948,7 @@ See also [TeX](#tex)
 ###Scilab
 
 * [Introduction to Scilab](http://forge.scilab.org/index.php/p/docintrotoscilab/downloads/)
+* [Writing Scilab Extensions](http://forge.scilab.org/index.php/p/docsciextensions/downloads/)
 
 ###Scratch
 * [Computer Science Concepts in Scratch](http://stwww.weizmann.ac.il/g-cs/scratch/scratch_en.html)