diff --git a/docs/1b/ece140.md b/docs/1b/ece140.md
index 0b122b2..2873021 100644
--- a/docs/1b/ece140.md
+++ b/docs/1b/ece140.md
@@ -453,4 +453,4 @@ Superposition must be summed at the end only, although individual components can
 3. Convert to time domain
 4. Apply KCL/KVL
 
-
+When applying source transformations, different equivalent circuits for **each frequency** must be calculated individually — reducing it to one equivalent circuit is not possible.