diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000000000000000000000000000000000000..e4a932a9e942873b02f16677487fe24e62e59f2d
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,9 @@
+[submodule "ulo/coq.8.9.0"]
+	path = ulo/libraries/coq
+	url = git@gl.mathhub.info:Coqxml/coq.8.9.0.git
+[submodule "ulo/Distribution"]
+	path = ulo/libraries/isabelle-distribution
+	url = git@gl.mathhub.info:Isabelle/Distribution.git
+[submodule "ulo/AFP"]
+	path = ulo/libraries/isabelle-afp
+	url = git@gl.mathhub.info:Isabelle/AFP.git
diff --git a/ulo/libraries/coq b/ulo/libraries/coq
new file mode 160000
index 0000000000000000000000000000000000000000..a9d7038b77f0356311f4b3b6f531458cb66a7e0e
--- /dev/null
+++ b/ulo/libraries/coq
@@ -0,0 +1 @@
+Subproject commit a9d7038b77f0356311f4b3b6f531458cb66a7e0e
diff --git a/ulo/libraries/isabelle-afp b/ulo/libraries/isabelle-afp
new file mode 160000
index 0000000000000000000000000000000000000000..1ce32ec014747e08d6e9782aed4cdd6631224fd6
--- /dev/null
+++ b/ulo/libraries/isabelle-afp
@@ -0,0 +1 @@
+Subproject commit 1ce32ec014747e08d6e9782aed4cdd6631224fd6
diff --git a/ulo/libraries/isabelle-distribution b/ulo/libraries/isabelle-distribution
new file mode 160000
index 0000000000000000000000000000000000000000..beb24f82b77007110f0568031d3ddaf75980be9e
--- /dev/null
+++ b/ulo/libraries/isabelle-distribution
@@ -0,0 +1 @@
+Subproject commit beb24f82b77007110f0568031d3ddaf75980be9e