diff --git a/experiment/references.md b/experiment/references.md
index f8a86eb..5a7c150 100644
--- a/experiment/references.md
+++ b/experiment/references.md
@@ -1,2 +1,5 @@
-### 1) https://en.wikipedia.org/wiki/Counter_(digital)
-### 2) M. Morris Mano, Digital Logic And Computer Design
+### 1. Mano, M. Morris. Digital logic and computer design. Pearson Education India, 2017.
+
+### 2. Website: 
+
+https://en.wikipedia.org/wiki/Digital_electronics