--- a/doc/libupnpp-ctl.txt
+++ b/doc/libupnpp-ctl.txt
@@ -120,7 +120,8 @@
 building the service objects directly).
 
 The library also has helper functions for helping with the independant
-implementation of a service interface.
+implementation of a service interface, obtained by deriving the base
+link:refdoc/html/classUPnPClient_1_1Service.html[Service class].
 
 == Predefined Service classes