diff --git a/notes/process-supervision.md b/notes/process-supervision.md
index e0e3c77..f2bbc2f 100644
--- a/notes/process-supervision.md
+++ b/notes/process-supervision.md
@@ -145,3 +145,7 @@ We have a similar distinction: the "system layer" of supervision vs. programs su
 other portions and/or by inferior syndicate-server instances (like inferior DBus/systemd
 instances). Maybe holding the *conceptual* distinction between agents and daemons is also
 worthwhile!
+
+
+"The Design and Implementation of the NetBSD rc.d system", Luke Mewburn,
+http://www.mewburn.net/luke/papers/rc.d.pdf