diff --git a/doc/index.rst b/doc/index.rst
index 91b2ae6..fb907b9 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -21,6 +21,22 @@ Contents:
    :maxdepth: 2
 
 
+References
+==========
+
+`HiC-Pro: an optimized and flexible pipeline for Hi-C data processing
+<http://link.springer.com/article/10.1186/s13059-015-0831-x/fulltext.html>`_
+\*N. Servant, N. Varoquaux, B.R. Lajoie, E. Viara, C.J. Chen, J.-P. Vert, E.
+Heard, J. Dekker, E. Barillot, Genome Biology 2015 
+
+Contacts
+========
+
+If you have any questions or suggestions, please email nelle dot varoquaux at
+ensmp dot fr, or open a ticket on `Github
+<https://github.com/hiclib/pastis/issues>`_
+
+
 
 Indices and tables
 ==================
diff --git a/examples/utils/README.txt b/examples/utils/README.txt
new file mode 100644
index 0000000..4c4e0a2
--- /dev/null
+++ b/examples/utils/README.txt
@@ -0,0 +1,6 @@
+.. _utils_examples:
+
+Utils
+-------------
+
+Examples concerning the :mod:`iced.utils` module.
diff --git a/examples/utils/plot_extract_sample_map.py b/examples/utils/plot_extract_sample_map.py
index a0c9bcf..4a11cf0 100644
--- a/examples/utils/plot_extract_sample_map.py
+++ b/examples/utils/plot_extract_sample_map.py
@@ -20,7 +20,7 @@
 m = ax.matshow(sub_counts, cmap="Blues", norm=colors.SymLogNorm(1),
                origin="bottom",
                extent=(0, len(sub_counts), 0, len(sub_counts)))
-[ax.axhline(i, linewidth=1, color="#000000") for i in lengths.cumsum()]
-[ax.axvline(i, linewidth=1, color="#000000") for i in lengths.cumsum()]
+[ax.axhline(i, linewidth=1, color="#000000") for i in sub_lengths.cumsum()]
+[ax.axvline(i, linewidth=1, color="#000000") for i in sub_lengths.cumsum()]
 cb = fig.colorbar(m)
 ax.set_title("Chromosomes I, IV and V of yeast")
diff --git a/examples/utils/plot_intra_inter_contact_maps.py b/examples/utils/plot_intra_inter_contact_maps.py
new file mode 100644
index 0000000..1e67db3
--- /dev/null
+++ b/examples/utils/plot_intra_inter_contact_maps.py
@@ -0,0 +1,41 @@
+import numpy as np
+import matplotlib.pyplot as plt
+from matplotlib import colors
+
+from iced import datasets
+from iced.utils import get_intra_mask
+from iced.utils import get_inter_mask
+
+"""
+Extracting parts of a contact map.
+
+This examples shows how to use a mask to plot only the inter or the intra
+contact map.
+
+"""
+
+# Loading a sample dataset
+counts, lengths = datasets.load_sample_yeast()
+intra_mask = get_intra_mask(lengths)
+inter_mask = get_inter_mask(lengths)
+
+fig, axes = plt.subplots(ncols=2, figsize=(12, 6))
+inter_counts = counts.copy()
+inter_counts[intra_mask] = np.nan
+intra_counts = counts.copy()
+intra_counts[inter_mask] = np.nan
+
+m = axes[0].matshow(intra_counts, cmap="Blues", norm=colors.SymLogNorm(1),
+                    origin="bottom",
+                    extent=(0, len(counts), 0, len(counts)))
+m = axes[1].matshow(inter_counts, cmap="Blues", norm=colors.SymLogNorm(1),
+                    origin="bottom",
+                    extent=(0, len(counts), 0, len(counts)))
+
+axes[0].set_title("Intra-chromosomal maps")
+axes[1].set_title("Inter-chromosomal maps")
+
+[axes[0].axhline(i, linewidth=1, color="#000000") for i in lengths.cumsum()]
+[axes[0].axvline(i, linewidth=1, color="#000000") for i in lengths.cumsum()]
+[axes[1].axhline(i, linewidth=1, color="#000000") for i in lengths.cumsum()]
+[axes[1].axvline(i, linewidth=1, color="#000000") for i in lengths.cumsum()]