I assume this task is about Wikidata-Query-Service

The licensing situation seems unclear for some of these databases. I only found this page, which only documents two of these endpoints.

• The data under /stw/ is ODbL 1.0 according to these pages.
• The data under /gnd/ is unclear to me. GND data itself is CC0 according to this page, but the endpoint may also include data from Geonames (CC-BY 3.0 according to this page) and Thema (a custom EDItEUR license according to this page).
• The /ebds/ and /repec/ endpoints aren’t mentioned at all on https://zbw.eu/beta/sparql-lab/about/.

Do you have any more information for us?

OK, I did not think about licenses - sorry!

• /gnd/ is just the dump of the CC0 set provided at https://data.dnb.de/opendata/. I did not include additional data.
• /repec/ are the authors and organization from repec.org. Their statement at http://repec.org/docs/RePEcDataUse.html is, well, not completely clear in terms of licensing.
• /ebds/ is a dataset by ZBW and other data providers which is to be pulished in the future. However, the licensing conditions are not yet defined.

So, when it's necessary to include only properyl licensed data, probably best is to skip /repec/ and /ebds/ for now. Most important currently is /stw/, which I want to use to create examples like this one representing a STW/Wikidata mapping. Would STW's ODbL license prohibit that?

I think @Smalyshev is the final authority on that, I just wanted to get started with some information that AFAIK he’ll need anyways :)

The page for nominating endpoints is here: https://www.wikidata.org/wiki/Wikidata:SPARQL_federation_input
It'd be nice to have licensing and documentation pages for each (more than one can have the same docs/license of course).