N2S3.md

 ### Description
 
-N2S3 is an open-source neuromorphic hardware simulator with the following properties:
+N2S3 [^1] is an open-source neuromorphic hardware simulator with the following properties:
 
 - **Event-Based**: Event based processing, in contrast to clock-based processing allows the local processing of each event, and high accuracy of timestamp.
 - **Scalable**: N2S3 uses the Akka project to enable massively concurrent programming. All simulator entities are (potentially) actors. This model fits well with the neural network processing paradigm. Thus a simulation is concurrent and can be distributed on a cluster.