I believe 'subjective' would work well.
"Subjectivity [refers to] a subject's personal perspective, feelings, beliefs, desires or discovery, as opposed to those made from an independent, objective, point of view"
I think that it nicely fits into your example sentence.
"I calculated agreement between subjective sources"
You said that the term you will use must represent a collection of 'non-mathematical' sources.
The word needs to represent a collection of non-mathematical
In my view, 'calculated' is not well suited to describe work with 'non-mathematical' things.
I calculated agreement between _ sources
May I suggest that you consider using a verb such as 'evaluated' instead of 'calculated'. In my opinion, 'compare' might be the most effective verb: Compare represents an evaluation of the similarities among the objects of comparison. It could replace both 'calculated' and 'agreement' - I compared subjective sources.
Merriam-Webster's first definition for 'compare': to represent as similar
American Heritage's first definition for 'compare': To consider or describe as similar, equal, or analogous; liken
I hope that this was helpful. Good luck