diff --git a/doc/ipython_notebooks/Degree.ipynb b/doc/ipython_notebooks/Degree.ipynb
index cbedf95..150a723 100644
--- a/doc/ipython_notebooks/Degree.ipynb
+++ b/doc/ipython_notebooks/Degree.ipynb
@@ -21,7 +21,7 @@
       ".. [1] JD Power, B Schlaggar, CN Lessov-Schlaggar, SE Petersen, \n",
       "    \"Evidence for Hubs in Human Functional Brain Networks\"\n",
       "    Neuron Volume 79, Issue 4, 21 August 2013, Pages 798\u2013813\n",
-      "    http://dx.doi.org/10.1016/j.neuron.2013.07.035"
+      "    https://doi.org/10.1016/j.neuron.2013.07.035"
      ]
     },
     {