During research, I often cite a passage from some website, a local document or org file. For context and later use, I always add the source reference after the block:
* Public transport
Buses are used a lot:
The urban bus system, the world's most common form of public transport, uses a network of scheduled routes to move people through the city, alongside cars, on the roads.
I would really like the referenced source to be an actual property of the block. I don't know if there is a way for that, or in which direction I should look for this. I've tried looking at header arguments and org-ref, but they do not seem really applicable to my specific requirement.
Is there a standardized or recommended way of annotating org blocks with source references?