diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -76,16 +76,17 @@ Contributions are always welcome!
 	* [Key-Value Databases (DynamoDB, Voldemort, Manhattan)](http://highscalability.com/anti-rdbms-list-distributed-key-value-stores)
 		* [Scaling Mapbox infrastructure with DynamoDB Streams](https://blog.mapbox.com/scaling-mapbox-infrastructure-with-dynamodb-streams-d53eabc5e972)
 		* [Manhattan: Twitter’s distributed key-value database](https://blog.twitter.com/engineering/en_us/a/2014/manhattan-our-real-time-multi-tenant-distributed-database-for-twitter-scale.html)
-	* [Document Databases (Cassandra, Vertica, Sybase IQ)](https://msdn.microsoft.com/en-us/magazine/hh547103.aspx)
+	* [Column Databases (Cassandra, HBase, Vertica, Sybase IQ)](https://aws.amazon.com/nosql/columnar/)
 		* [Consistent Hashing in Cassandra](https://blog.imaginea.com/consistent-hashing-in-cassandra/)
 		* [When NOT to use Cassandra?](https://stackoverflow.com/questions/2634955/when-not-to-use-cassandra)
 		* [Storing Images in Cassandra at Walmart Scale](https://medium.com/walmartlabs/building-object-store-storing-images-in-cassandra-walmart-scale-a6b9c02af593)
 		* [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)
-	* [Graph Databases (MongoDB, CouchDB, Neo4j)](https://neo4j.com/blog/neo4j-scalability-infographic/)
+	* [Document Databases (MongoDB, 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)
+	* [Graph Databases (Neo4j)](https://neo4j.com/blog/neo4j-scalability-infographic/)		
 		* [Neo4j at Airbnb](https://neo4j.com/users/airbnb/)
 	* [Datastructure Databases (Redis, Hazelcast)](https://db-engines.com/en/system/Hazelcast%3BMemcached%3BRedis)
 		* [How Twitter Uses Redis To Scale](http://highscalability.com/blog/2014/9/8/how-twitter-uses-redis-to-scale-105tb-ram-39mm-qps-10000-ins.html)