diff --git a/materials/Graphene.json b/materials/Graphene.json
index 9a24fbd..3166f8b 100644
--- a/materials/Graphene.json
+++ b/materials/Graphene.json
@@ -84,7 +84,9 @@
     "isNonPeriodic": false,
     "external": {
         "id": "mp-1040425",
-        "source": "https://next-gen.materialsproject.org/materials/",
+        "source": "materials project",
+        "doi": "10.17188/1405723",
+        "url": "https://next-gen.materialsproject.org/materials/mp-1040425/",
         "origin": true
     }
 }
diff --git a/materials/Na4Cl4.json b/materials/Na4Cl4.json
index e5c0bed..2eaaac4 100644
--- a/materials/Na4Cl4.json
+++ b/materials/Na4Cl4.json
@@ -155,7 +155,9 @@
     "isNonPeriodic": false,
     "external": {
         "id": "mp-22862",
-        "source": "https://next-gen.materialsproject.org/materials/",
+        "source": "materials project",
+        "doi": "10.17188/1199028",
+        "url": "https://next-gen.materialsproject.org/materials/mp-22862/",
         "origin": true
     }
 }
diff --git a/materials/Si.json b/materials/Si.json
index e868214..d8d41b2 100644
--- a/materials/Si.json
+++ b/materials/Si.json
@@ -46,7 +46,9 @@
     "isNonPeriodic": false,
     "external": {
         "id": "mp-149",
-        "source": "https://next-gen.materialsproject.org/materials/",
+        "source": "materials project",
+        "doi": "10.17188/1190959",
+        "url": "https://next-gen.materialsproject.org/materials/mp-149/",
         "origin": true
     }
 }
diff --git a/materials/WS2.json b/materials/WS2.json
index cc74151..262af68 100644
--- a/materials/WS2.json
+++ b/materials/WS2.json
@@ -96,7 +96,9 @@
     "isNonPeriodic": false,
     "external": {
         "id": "mp-224",
-        "source": "https://next-gen.materialsproject.org/materials/",
+        "source": "materials project",
+        "doi": "10.17188/1197614",
+        "url": "https://next-gen.materialsproject.org/materials/mp-224/",
         "origin": true
     }
 }
diff --git a/materials/h-BN.json b/materials/h-BN.json
index 6aeb67f..1ce4300 100644
--- a/materials/h-BN.json
+++ b/materials/h-BN.json
@@ -84,7 +84,9 @@
     "isNonPeriodic": false,
     "external": {
         "id": "mp-984",
-        "source": "https://next-gen.materialsproject.org/materials/",
+        "source": "materials project",
+        "doi": "10.17188/1281942",
+        "url": "https://next-gen.materialsproject.org/materials/mp-984/",
         "origin": true
     }
 }