Are they under a single topic?

Materials can be under the same topic or not based on the collecting perspective (as the topic), for example[1], [2]:

1. If the topic discusses GTD methodology, then the followings in the same topic:

   • What is GTD
   • comparison of GTD against other methods
   • general principles
   • recommendation tools

2. but if the topic is about GTD workflow, then the followings are:

   • general principles

   • recommendation tools are in one note

     but introduction of GTD or comparison are not

3. Similarly, if the focus is about how to apply GTD, then we can consider these two are under the same topic:

   • general principles
   • recommendation tools can be re-mixed horizontally (which tool is best for which step, different practices of each step with different tools, etc).

Bibliography