diff --git a/Test_Cases/readme b/Test_Cases/readme
index 5393777..7424f2e 100644
--- a/Test_Cases/readme
+++ b/Test_Cases/readme
@@ -13,6 +13,9 @@ Same steps can be repeated for test case 2 and 3 but everytime a different ip.ad
 
 The testCase1.png, testCase2.png, and testCase3.png shows the output on wireshark.
 
+References:
+1. This is the link to the Peterson and Davie Computer Networks book (https://titania.eng.monash.edu/netperf/docs/computer-networks-peterson-davie-v6.0.pdf)
+