So in my NA list (Focused on single project view) should I be placing reference/project support material in this list ? I use OmniFocus and have a context called "Reference". So when i view my list i can see a greyed out area, letting me know its a reference item. But should i have another project or subproject with a collection of project support material ? current workflow example:

Project: Create Learn French iBook
NA x
NA z
Reference: a