src/Doc/Tutorial/document/basics.tex

--- a/src/Doc/Tutorial/document/basics.tex	Mon Feb 12 13:27:30 2018 +0100
+++ b/src/Doc/Tutorial/document/basics.tex	Mon Feb 12 14:13:54 2018 +0100
@@ -95,7 +95,7 @@
 For the more adventurous, there is the \emph{Archive of Formal Proofs},
 a journal-like collection of more advanced Isabelle theories:
 \begin{center}\small
-    \url{http://afp.sourceforge.net/}
+    \url{https://isa-afp.org/}
 \end{center}
 We hope that you will contribute to it yourself one day.%
 \index{theories|)}