diff --git a/README.md b/README.md
index dd40077..abf4e0f 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,7 @@ Gathering information for a centralized open data live traffic platform.
 ## sources
 
 - https://autobahn.api.bund.dev
+- some kind of anonymized user-contributed data via existing/participating apps (OsmAnd / OM / other plugin)
 
 ## alternatives