file:a/index.md -> file:b/index.md
--- a/index.md
+++ b/index.md
@@ -365,10 +365,6 @@
 # Graph (relationships and networks) Data Tools {#graph-relationships-and-networks-data-tools}
 Graph data can be very valuable for finding communities, hubs and connections between entities (the 6 degrees of separation). This is through the techniques of Social Network Analysis.
-    - http://www.slideshare.net/OReillyStrata/visualizing-networks-beyond-the-hairball
-    - http://blog.sciencenet.cn/blog-554179-622011.html SNA tools catalog
-    - https://github.com/jacomyal/osdc2012-sigmajs-demo sigmajs filtering/searching
 ## Analysis
@@ -397,6 +393,9 @@
 ## Visualisation
+Proper visualisation of networks can be hard as described in this presentation [Visualising Networks: Beyond the Hairball](http://www.slideshare.net/OReillyStrata/visualizing-networks-beyond-the-hairball)
 ###  Tree/Hierarchy visualisation
 Sometimes when you analyse a network what you actually have is a tree/hierarchy with no interconnections.
 In these cases, it's faster and more visually effective to use a Tree visualisation.
@@ -418,4 +417,4 @@
 ### [sigma.js](http://sigmajs.org/)
 [![](img/How-to-participate-in-GovHack_html_m6006eaf3-300x130.jpg "Sigma.js Screenshot")](img/How-to-participate-in-GovHack_html_m6006eaf3.jpg)Javascript graph viewer for displaying graphs on webpages without any other plugins/applications required. It can use GEXF files exported from tools like neo4j, gephi or NetworkX.
+ It's also possible to [filter/search the displayed network in sigma.js](https://github.com/jacomyal/osdc2012-sigmajs-demo)