DOC refer to DOI for colormap IBM paper.

NelleV · web-flow · commit 846f9ab131ec · 2018-08-18T10:36:16.000-07:00
diff --git a/tutorials/colors/colormaps.py b/tutorials/colors/colormaps.py
@@ -417,4 +417,4 @@ def plot_color_gradients(cmap_category, cmap_list):
 # .. [bw] http://www.tannerhelland.com/3643/grayscale-image-algorithm-vb6/
 # .. [colorblindness] http://www.color-blindness.com/
 # .. [vischeck] http://www.vischeck.com/vischeck/
-# .. [IBM] https://archive.is/fmYgZ
+# .. [IBM] https://ieeexplore.ieee.org/document/480803/
