This is a bit different. Nodes are generally themes which you identify in literature. For example: If you identify research gaps in literature then you create node as "research gap". In other articles or paper you can find similar research gaps which you can code in same node "research gaps". Each paper or article can be coded as case which gives you set of information from a source. Case node is useful when you want to create tables as 

               Research Gap 1                  Research gap 2             Research gap 3

Article 1

Article 2

Article 3

Article 4

In this way you can compare and contrast the research gaps for your thesis.

Watch following video for details. 

https://www.youtube.com/watch?v=6bIX2b-pbwI

Thanks,

Vikash

Thank you very much for the explanation and the link

Welcome. What is your research topic.