diff --git a/doc/examples/bundle_registration.py b/doc/examples/bundle_registration.py
index 66391fe823..9e5cdd618f 100644
--- a/doc/examples/bundle_registration.py
+++ b/doc/examples/bundle_registration.py
@@ -83,6 +83,9 @@ def show_both_bundles(bundles, colors=None, show=False, fname=None):
 
    **After bundle registration**.
 
+.. [Garyfallidis15] Garyfallidis et. al, "Robust and efficient linear
+                    registration of white-matter fascicles in the space
+                    of streamlines", Neuroimage, 117:124-140, 2015.
 .. [Garyfallidis14] Garyfallidis et. al, "Direct native-space fiber bundle
                     alignment for group comparisons", ISMRM, 2014.