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@@ -25,11 +25,12 @@ Contributions are always welcome!
 
 ## Principles
 * [CAP Theorem and Trade-offs](http://robertgreiner.com/2014/08/cap-theorem-revisited/)	
-* [Scaling Up versus Scaling Out](https://blogs.technet.microsoft.com/admoore/2015/02/17/scaling-out-vs-scaling-up/)
+* [Scaling Up and Scaling Out](https://blogs.technet.microsoft.com/admoore/2015/02/17/scaling-out-vs-scaling-up/)
 * [Best Practices for Scaling Out](https://blog.openshift.com/best-practices-for-horizontal-application-scaling/)
 * [Understanding Latency](http://highscalability.com/latency-everywhere-and-it-costs-you-sales-how-crush-it)
 * [Maximal Throughput with Acceptable Latency (Dropbox case)](https://blogs.dropbox.com/tech/2017/09/optimizing-web-servers-for-high-throughput-and-low-latency/)
 * [ACID and BASE](https://neo4j.com/blog/acid-vs-base-consistency-models-explained/)
+* [Synchronous and Asynchronous](https://blogs.msdn.microsoft.com/csliu/2009/08/04/inside-scalable-io-model-in-sync-async-way/)
 * [Architecture Issues When Scaling Web Applications: Bottlenecks, Database, CPU, IO](http://highscalability.com/blog/2014/5/12/4-architecture-issues-when-scaling-web-applications-bottlene.html)	
 * [Performance and Scalability patterns](https://docs.microsoft.com/en-us/azure/architecture/patterns/category/performance-scalability)
 * [Advantages and Drawbacks of Microservices](https://cloudacademy.com/blog/microservices-architecture-challenge-advantage-drawback/)
@@ -212,6 +213,7 @@ Contributions are always welcome!
 * [Selecting a cloud provider at Etsy](https://codeascraft.com/2018/01/04/selecting-a-cloud-provider/)
 * [Architecture of Tripod (Flickr’s Backend)](https://yahooeng.tumblr.com/post/157200523046/introducing-tripod-flickrs-backend-refactored)
 * [How eBay's Shopping Cart used compression techniques to solve network I/O bottlenecks](https://www.ebayinc.com/stories/blogs/tech/how-ebays-shopping-cart-used-compression-techniques-to-solve-network-io-bottlenecks/)
+* [Optimizing web servers for high throughput and low latency at Dropbox](https://blogs.dropbox.com/tech/2017/09/optimizing-web-servers-for-high-throughput-and-low-latency/)
 
 ## Books
 * [The Art of Scalability](http://theartofscalability.com/)