diff --git a/base/lower_case.cpp b/base/lower_case.cpp
index 7479a478cf..cef2d5bc2f 100644
--- a/base/lower_case.cpp
+++ b/base/lower_case.cpp
@@ -1,3 +1,7 @@
+/// Performs full case folding for string to make it search-compatible according
+/// to rules in ftp://ftp.unicode.org/Public/UNIDATA/CaseFolding.txt
+/// This beautiful code has been inspired by Zurich area in 2011 (Alex Zolotarev).
+
 #include "string_utils.hpp"
 
 namespace strings
diff --git a/base/normalize_unicode.cpp b/base/normalize_unicode.cpp
index 192b54b547..55f99e3d85 100644
--- a/base/normalize_unicode.cpp
+++ b/base/normalize_unicode.cpp
@@ -1,3 +1,7 @@
+/// Performs NFKD - Compatibility decomposition for Unicode according
+/// to rules in ftp://ftp.unicode.org/Public/UNIDATA/UnicodeData.txt
+/// This beautiful code has been inspired by Zurich area in 2011 (Alex Zolotarev).
+
 #include "string_utils.hpp"
 
 namespace strings
diff --git a/base/string_utils.hpp b/base/string_utils.hpp
index c1a0208dff..0a28098390 100644
--- a/base/string_utils.hpp
+++ b/base/string_utils.hpp
@@ -29,12 +29,17 @@ public:
   bool IsEqualAscii(char const * s) const;
 };
 
-UniString MakeLowerCase(UniString const & s);
+/// Performs full case folding for string to make it search-compatible according
+/// to rules in ftp://ftp.unicode.org/Public/UNIDATA/CaseFolding.txt
 /// For implementation @see base/lower_case.cpp
 void MakeLowerCase(UniString & s);
-UniString Normalize(UniString const & s);
+UniString MakeLowerCase(UniString const & s);
+
+/// Performs NFKD - Compatibility decomposition for Unicode according
+/// to rules in ftp://ftp.unicode.org/Public/UNIDATA/UnicodeData.txt
 /// For implementation @see base/normilize_unicode.cpp
 void Normalize(UniString & s);
+UniString Normalize(UniString const & s);
 
 /// Counts number of start symbols in string s (that is not lower and not normalized) that maches
 /// to lower and normalized string low_s. If s doen't starts with low_s then returns 0; otherwise