diff --git a/systems/mws.md b/systems/mws.md
index 77920cce4a3e74c6a8674fe3fc6aafe9b4058aa9..0d1c224589df04b2c7a553eae5cee78f245965c8 100644
--- a/systems/mws.md
+++ b/systems/mws.md
@@ -21,4 +21,11 @@ publink: http://kwarc.github.io/bibs/mws
 
 The MathWebSearch system (MWS) is a content-based search engine for mathematical
 formulae. It indexes MathML formulae, using a technique derived from automated theorem
-proving: Substitution Tree Indexing. 
+proving: Substitution Tree Indexing. With this indexing technique MWS can answer
+unification queries extremely efficiently (30-100 ms) on large sets of formulae (in the
+Gigaformula range); but the index (up to 50GiB) needs to be kept in main memory.
+
+MWS is the [formula search engine](https://zbmath.org/formulae/) employed in
+[Zentralblatt Math](http://zbmath.org); see a
+[demo on a mathematical subset](http://arxivsearch.mathweb.org) of the
+[arXMLiv data set](/projects/arXMLiv/) [further demos](http://search.mathweb.org).