diff --git a/src/@dseries/nanstd.m b/src/@dseries/nanstd.m
index f3e23b02db1849a9182c894cb3a35d5829b28b44..60712d657930a1a1e6420e357943e11141c6b4e3 100644
--- a/src/@dseries/nanstd.m
+++ b/src/@dseries/nanstd.m
@@ -9,6 +9,9 @@ function s = nanstd(o, geometric) % --*-- Unitary tests --*--
 %
 % OUTPUTS
 % - s             1*vobs(o) vector of doubles.
+%
+% REMARKS
+% See https://en.wikipedia.org/wiki/Geometric_standard_deviation for the definition of the geometric standard deviation.
 
 % Copyright © 2020 Dynare Team
 %