diff --git a/images/etherpad/Dockerfile b/images/etherpad/Dockerfile
index 7c5e424..f91a1bf 100644
--- a/images/etherpad/Dockerfile
+++ b/images/etherpad/Dockerfile
@@ -29,6 +29,7 @@ ENV NODE_VERSION lts/erbium
 # lts-erbium = Node.js 12.x
 # We speculate that our problems with Etherpad are because we're using a newer version of Node.js..... :-/
 # nvm needs curl to download versions of Node.js
+# Ref https://stackoverflow.com/a/66521281/1460422
 
 RUN install_packages ca-certificates curl 
 RUN curl -sSL -o - https://raw.githubusercontent.com/nvm-sh/nvm/v0.38.0/install.sh | bash || true