diff --git a/book/features/HTML_javascript.md b/book/features/HTML_javascript.md
index 633fcc4..e76255d 100644
--- a/book/features/HTML_javascript.md
+++ b/book/features/HTML_javascript.md
@@ -13,4 +13,6 @@ This could be for example interactive 3d figures:
 
 Or other interactive graphs:
 
-<iframe src="../_static/element_pdf_and_cdf.html" width="600" height="300" frameborder="0"></iframe>
\ No newline at end of file
+<iframe src="../_static/element_pdf_and_cdf.html" width="600" height="300" frameborder="0"></iframe>
+
+<iframe src="https://openla.ewi.tudelft.nl/applet/lines_and_planes/normal_equation_plane_origin?iframe=true" allow="fullscreen" loading="lazy" frameborder="0"></iframe>
\ No newline at end of file