diff --git a/include/evalhyd/detail/probabilist/brier.hpp b/include/evalhyd/detail/probabilist/brier.hpp
index 338c08bfc8184208c1d698da967c73da9eac60f8..da86bf6bb87eb006ccf5254b63aacb5d69f3b6a5 100644
--- a/include/evalhyd/detail/probabilist/brier.hpp
+++ b/include/evalhyd/detail/probabilist/brier.hpp
@@ -6,6 +6,13 @@
 #include <xtensor/xmasked_view.hpp>
 
 
+// NOTE ------------------------------------------------------------------------
+// All equations in metrics below are following notations from
+// "Wilks, D. S. (2011). Statistical methods in the atmospheric sciences.
+// Amsterdam; Boston: Elsevier Academic Press. ISBN: 9780123850225".
+// In particular, pp. 302-303, 332-333.
+// -----------------------------------------------------------------------------
+
 namespace evalhyd
 {
     namespace probabilist
diff --git a/include/evalhyd/detail/probabilist/contingency.hpp b/include/evalhyd/detail/probabilist/contingency.hpp
index 6ef68ff7f9fd0e2d40415e604c27162dd7073347..75964ee5e272609fcb1366970e888c8f6fd40fcb 100644
--- a/include/evalhyd/detail/probabilist/contingency.hpp
+++ b/include/evalhyd/detail/probabilist/contingency.hpp
@@ -6,6 +6,7 @@
 #include <xtensor/xmasked_view.hpp>
 #include <xtensor/xmath.hpp>
 
+
 // NOTE ------------------------------------------------------------------------
 // All equations in metrics below are following notations from
 // "Wilks, D. S. (2011). Statistical methods in the atmospheric sciences.
@@ -13,7 +14,6 @@
 // In particular, pp. 302-303, 332-333.
 // -----------------------------------------------------------------------------
 
-
 namespace evalhyd
 {
     namespace probabilist
diff --git a/include/evalhyd/detail/probabilist/quantiles.hpp b/include/evalhyd/detail/probabilist/quantiles.hpp
index b4963c5a5c5c94df1f5ae6ba908d58cbe86f6134..184f0d35f48eb8c799c77ef24ba5e1e838bec2f9 100644
--- a/include/evalhyd/detail/probabilist/quantiles.hpp
+++ b/include/evalhyd/detail/probabilist/quantiles.hpp
@@ -6,6 +6,13 @@
 #include <xtensor/xsort.hpp>
 
 
+// NOTE ------------------------------------------------------------------------
+// All equations in metrics below are following notations from
+// "Wilks, D. S. (2011). Statistical methods in the atmospheric sciences.
+// Amsterdam; Boston: Elsevier Academic Press. ISBN: 9780123850225".
+// In particular, pp. 302-303, 332-333.
+// -----------------------------------------------------------------------------
+
 namespace evalhyd
 {
     namespace probabilist