diff --git a/DIRECTORY.md b/DIRECTORY.md
index f0a34a553..2a5ac5584 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -422,6 +422,7 @@
   * [Resistor Color Code](electronics/resistor_color_code.py)
   * [Resistor Equivalence](electronics/resistor_equivalence.py)
   * [Resonant Frequency](electronics/resonant_frequency.py)
+  * [Star Delta Transform](electronics/star_delta_transform.py)
   * [Wheatstone Bridge](electronics/wheatstone_bridge.py)
 
 ## File Transfer