diff --git a/.gitmodules b/.gitmodules
index f973b58c22..186a027f19 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,18 @@
 [submodule "src/ExternalLibs/professor"]
 	path = src/ExternalLibs/professor
 	url = https://gitlab.com/hepcedar/professor.git
+[submodule "src/ExternalLibs/lhapdf6"]
+	path = src/ExternalLibs/lhapdf6
+	url = https://gitlab.com/hepcedar/lhapdf.git
+[submodule "src/ExternalLibs/libxml2"]
+	path = src/ExternalLibs/libxml2
+	url = https://github.com/GNOME/libxml2.git
+[submodule "src/ExternalLibs/pythia8"]
+	path = src/ExternalLibs/pythia8
+	url = https://gitlab.com/Pythia8/releases.git
+[submodule "src/ExternalLibs/log4cpp"]
+	path = src/ExternalLibs/log4cpp
+	url = https://github.com/orocos-toolchain/log4cpp.git
+[submodule "src/ExternalLibs/geant4"]
+	path = src/ExternalLibs/geant4
+	url = https://github.com/Geant4/geant4.git
diff --git a/src/ExternalLibs/geant4 b/src/ExternalLibs/geant4
new file mode 160000
index 0000000000..eb12faf1a1
--- /dev/null
+++ b/src/ExternalLibs/geant4
@@ -0,0 +1 @@
+Subproject commit eb12faf1a12ad7f2679c66b8afee3dc404852f7c
diff --git a/src/ExternalLibs/lhapdf6 b/src/ExternalLibs/lhapdf6
new file mode 160000
index 0000000000..6292254c1d
--- /dev/null
+++ b/src/ExternalLibs/lhapdf6
@@ -0,0 +1 @@
+Subproject commit 6292254c1dccea242ea0aafba81a6b096087a197
diff --git a/src/ExternalLibs/libxml2 b/src/ExternalLibs/libxml2
new file mode 160000
index 0000000000..13a3df99ff
--- /dev/null
+++ b/src/ExternalLibs/libxml2
@@ -0,0 +1 @@
+Subproject commit 13a3df99ffe2521a903f270abb33aa7092b34147
diff --git a/src/ExternalLibs/log4cpp b/src/ExternalLibs/log4cpp
new file mode 160000
index 0000000000..a920aca459
--- /dev/null
+++ b/src/ExternalLibs/log4cpp
@@ -0,0 +1 @@
+Subproject commit a920aca4593cb7c2f844d35fbc314c51aa9e4c96
diff --git a/src/ExternalLibs/pythia8 b/src/ExternalLibs/pythia8
new file mode 160000
index 0000000000..83a5c9986f
--- /dev/null
+++ b/src/ExternalLibs/pythia8
@@ -0,0 +1 @@
+Subproject commit 83a5c9986f30746cfb390435a9b10ac55a758fca