diff --git a/README.md b/README.md
index 4157625..749c1c7 100644
--- a/README.md
+++ b/README.md
@@ -158,11 +158,12 @@ A curated list of selected readings to illustrate Scalability, Availability, and
 		* [Cassandra at Instagram](https://www.slideshare.net/DataStax/cassandra-at-instagram-2016)
 		* [How Yelp Scaled Ad Analytics with Cassandra](https://engineeringblog.yelp.com/2016/08/how-we-scaled-our-ad-analytics-with-cassandra.html)
 		* [How Discord Stores Billions of Messages with Cassandra](https://blog.discordapp.com/how-discord-stores-billions-of-messages-7fa6ec7ee4c7)
-	* [Document Databases (MongoDB, CouchDB)](https://msdn.microsoft.com/en-us/magazine/hh547103.aspx)
+	* [Document Databases (MongoDB, SimpleDB, CouchDB)](https://msdn.microsoft.com/en-us/magazine/hh547103.aspx)
 		* [eBay: Building Mission-Critical Multi-Data Center Applications with MongoDB](https://www.mongodb.com/blog/post/ebay-building-mission-critical-multi-data-center-applications-with-mongodb)
 		* [MongoDB at Baidu: Multi-Tenant Cluster Storing 200+ Billion Documents across 160 Shards](https://www.mongodb.com/blog/post/mongodb-at-baidu-powering-100-apps-across-600-nodes-at-pb-scale)
 		* [The AWS and MongoDB Infrastructure of Parse (acquired by Facebook)](https://medium.baqend.com/parse-is-gone-a-few-secrets-about-their-infrastructure-91b3ab2fcf71)
 		* [Couchbase Ecosystem at LinkedIn](https://engineering.linkedin.com/blog/2017/12/couchbase-ecosystem-at-linkedin)
+		* [SimpleDB at Zendesk](https://medium.com/zendesk-engineering/resurrecting-amazon-simpledb-9404034ec506)
 	* [Graph Databases](https://www.ibm.com/developerworks/library/cl-graph-database-1/index.html)		
 		* [Neo4j case studies with Walmart, eBay, AirBnB, NASA, etc](https://neo4j.com/customers/)
 		* [FlockDB: Distributed Graph Database for Storing Adjancency Lists at Twitter](https://blog.twitter.com/engineering/en_us/a/2010/introducing-flockdb.html)