diff --git a/18-context-mngr/lispy/README.md b/18-context-mngr/lispy/README.md
index 69e042c..cf18e3b 100644
--- a/18-context-mngr/lispy/README.md
+++ b/18-context-mngr/lispy/README.md
@@ -2,7 +2,7 @@
 
 This directory contains 3 versions of
 [Peter Norvig's `lis.py` interpreter](https://norvig.com/lispy.html)
-for Scheme.
+for a subset of [Scheme](https://en.wikipedia.org/wiki/Scheme_(programming_language)).
 
 * `original/`: Norvig's `lis.py` unchanged, `lispy.py` with
 [minor changes](https://github.com/norvig/pytudes/pull/106) to run on Python 3,