diff --git a/README.md b/README.md
index 9a4d112..dca8df2 100644
--- a/README.md
+++ b/README.md
@@ -91,12 +91,12 @@ An awesome list about Software Defined Networks (SDN)
 - [ONOS](http://onosproject.org) - Open Network Operating System.
 - [Open MUL](http://www.openmul.org/openmul-controller.html) - A lightweight SDN/Openflow controller written almost entirely in C from scratch.
 - [Open Security Controller](https://www.opensecuritycontroller.org/) - Software-defined security orchestration solution that automates deployment of virtualized network security functions, like next-generation firewall, intrusion prevention systems and application data controllers
-- [OpenContrail](http://www.opencontrail.org/) - A SDN project that utilizes SDN & NFV and provides all the necessary components for network virtualization.
+- [OpenContrail](https://tungsten.io/opencontrail-is-now-tungsten-fabric/) - A SDN project that utilizes SDN & NFV and provides all the necessary components for network virtualization.
 - [OpenDaylight](https://www.opendaylight.org) - OpenDaylight Platform
 - [OVN](http://www.openvswitch.org//support/slides/OVN-Vancouver.pdf) - OVN: Open Virtual Network for Open vSwitch
 - [POX](https://github.com/noxrepo/pox) - An open source development platform for Python-based software-defined networking (*SDN*) control applications.
 - [Ravel](https://github.com/ravel-net/ravel) - A software-defined networking (SDN) controller that uses a standard SQL database to represent the network.
-- [Ryu](https://osrg.github.io/ryu) - A component-based software defined networking framework.
+- [Ryu](https://ryu-sdn.org/) - A component-based software defined networking framework.
 - [Trema](https://trema.github.io/trema/) - A full-stack, easy-to-use framework for developing OpenFlow controllers in Ruby and C.
 - [Vyatta](https://github.com/BRCDcomm/BVC/) - The first commercial Controller built directly from OpenDaylight.
 
@@ -195,7 +195,7 @@ It is designed to run on any processors. The first supported CPU was Intel x86 a
 - [DevOps for Networking](https://www.packtpub.com/networking-and-servers/devops-networking)
 - [Network Algorithmics：An Interdisciplinary Approach to Designing Fast Networked Devices](https://doc.lagout.org/network/Network%20Algorithmics%20An%20Interdisciplinary%20Approach%20to%20Designing%20Fast%20Networked%20Devices.pdf)
 - [Network Programmability and Automation Skills for the Next-Generation Network Engineer](http://shop.oreilly.com/product/0636920042082.do)
-- [SDN: Software Defined Networks: An Authoritative Review of Network Programmability Technologies](https://www.amazon.com/SDN-Software-Networks-Thomas-Nadeau/dp/1449342302/&tag=eltale-20)
+- [SDN: Software Defined Networks: An Authoritative Review of Network Programmability Technologies](https://www.oreilly.com/library/view/sdn-software-defined/9781449342425/)
 - [SDN网络指南](https://feisky.gitbooks.io/sdn/)(OpenSource Book in Chinese by Pengfei Ni)
 - [SDN核心技术剖析和实战指南](http://www.sdnlab.com/book/9480.html)
 - [Software Defined Networking with OpenFlow](https://www.packtpub.com/networking-and-servers/software-defined-networking-openflow)