If you have any documents, even if you aren't willing to sell or trade them, I would appreciate your contacting me, as I am interested in compiling a census.
Also, if you have any collateral documents or information, I'd be interested. Based upon the few articles that have been written (at least in English language publications), there is very little concretely known about these; much is speculative. There has even been conjecture that these are contrived/fantasies. No one knows for certain.
Example of a document shown below.