diff --git a/networks/notes/03-cookies-dns-tcp.md b/networks/notes/03-cookies-dns-tcp.md
index f92df3b..484e8b9 100644
--- a/networks/notes/03-cookies-dns-tcp.md
+++ b/networks/notes/03-cookies-dns-tcp.md
@@ -186,4 +186,5 @@ The fields in a TCP header are:
 | Optimal use            | Used by HTTPS, HTTP, SMTP, POP, FTP, etc                                                                        | Video conferencing, streaming, DNS, VoIP, etc                                                      |
 
 ## Reading list
-* [Cookies in depth](https://humanwhocodes.com/blog/2009/05/05/http-cookies-explained/)
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+* [Cookies in depth](https://humanwhocodes.com/blog/2009/05/05/http-cookies-explained/)
+* [Sliding Window](http://www.cs.uni.edu/~diesburg/courses/cs3470_fa14/sessions/s29/s29.pdf)
\ No newline at end of file