diff --git a/src/Country/CountryAlpha2.php b/src/Country/CountryAlpha2.php
index bf6fb11..7f72036 100644
--- a/src/Country/CountryAlpha2.php
+++ b/src/Country/CountryAlpha2.php
@@ -7,6 +7,7 @@
 
 /**
  * @source https://www.iso.org/obp/ui/#search/code/
+ * @standard ISO3166_1
  */
 enum CountryAlpha2: string
 {
diff --git a/src/Country/CountryAlpha3.php b/src/Country/CountryAlpha3.php
index c76f1b9..5a80eb9 100644
--- a/src/Country/CountryAlpha3.php
+++ b/src/Country/CountryAlpha3.php
@@ -7,6 +7,7 @@
 
 /**
  * @source https://www.iso.org/obp/ui/#search/code/
+ * @standard ISO3166_1
  */
 enum CountryAlpha3: string
 {
diff --git a/src/Country/CountryName.php b/src/Country/CountryName.php
index 66bd9de..0574377 100644
--- a/src/Country/CountryName.php
+++ b/src/Country/CountryName.php
@@ -7,6 +7,7 @@
 
 /**
  * @source https://www.iso.org/obp/ui/#search/code/
+ * @standard ISO3166_1
  */
 enum CountryName: string
 {
diff --git a/src/Country/CountryNumeric.php b/src/Country/CountryNumeric.php
index 86e91a9..c2fee9a 100644
--- a/src/Country/CountryNumeric.php
+++ b/src/Country/CountryNumeric.php
@@ -7,6 +7,7 @@
 
 /**
  * @source https://www.iso.org/obp/ui/#search/code/
+ * @standard ISO3166_1
  */
 enum CountryNumeric: string
 {
diff --git a/src/Currency/CurrencyAlpha3.php b/src/Currency/CurrencyAlpha3.php
index 8a92ea2..cd7ef0b 100644
--- a/src/Currency/CurrencyAlpha3.php
+++ b/src/Currency/CurrencyAlpha3.php
@@ -9,6 +9,7 @@
  * @source https://www.iso.org/iso-4217-currency-codes.html
  * @source https://www.six-group.com/en/products-services/financial-information/data-standards.html
  * @source https://www.six-group.com/dam/download/financial-information/data-center/iso-currrency/lists/list_one.xml
+ * @standard ISO4217
  */
 enum CurrencyAlpha3: string
 {
diff --git a/src/Currency/CurrencyName.php b/src/Currency/CurrencyName.php
index f083679..6986e2c 100644
--- a/src/Currency/CurrencyName.php
+++ b/src/Currency/CurrencyName.php
@@ -9,6 +9,7 @@
  * @source https://www.iso.org/iso-4217-currency-codes.html
  * @source https://www.six-group.com/en/products-services/financial-information/data-standards.html
  * @source https://www.six-group.com/dam/download/financial-information/data-center/iso-currrency/lists/list_one.xml
+ * @standard ISO4217
  */
 enum CurrencyName: string
 {
diff --git a/src/Currency/CurrencyNumeric.php b/src/Currency/CurrencyNumeric.php
index 654cbbb..1704489 100644
--- a/src/Currency/CurrencyNumeric.php
+++ b/src/Currency/CurrencyNumeric.php
@@ -9,6 +9,7 @@
  * @source https://www.iso.org/iso-4217-currency-codes.html
  * @source https://www.six-group.com/en/products-services/financial-information/data-standards.html
  * @source https://www.six-group.com/dam/download/financial-information/data-center/iso-currrency/lists/list_one.xml
+ * @standard ISO4217
  */
 enum CurrencyNumeric: string
 {
diff --git a/src/InternationalCallPrefix/InternationalCallPrefix.php b/src/InternationalCallPrefix/InternationalCallPrefix.php
index 1d18225..dbbbe37 100644
--- a/src/InternationalCallPrefix/InternationalCallPrefix.php
+++ b/src/InternationalCallPrefix/InternationalCallPrefix.php
@@ -3,6 +3,9 @@
 
 namespace PrinsFrank\Standards\InternationalCallPrefix;
 
+/**
+ * @standard ITU_T_E_164
+ */
 enum InternationalCallPrefix: string
 {
     case _0    = '0';
diff --git a/src/Language/LanguageAlpha2.php b/src/Language/LanguageAlpha2.php
index 7e60345..02e646e 100644
--- a/src/Language/LanguageAlpha2.php
+++ b/src/Language/LanguageAlpha2.php
@@ -8,6 +8,7 @@
 /**
  * @source https://www.iso.org/iso-639-language-codes.html
  * @source http://www.loc.gov/standards/iso639-2/php/code_list.php
+ * @standard ISO639_1
  */
 enum LanguageAlpha2: string
 {
diff --git a/src/Language/LanguageAlpha3Bibliographic.php b/src/Language/LanguageAlpha3Bibliographic.php
index 1ab5b27..ba7b860 100644
--- a/src/Language/LanguageAlpha3Bibliographic.php
+++ b/src/Language/LanguageAlpha3Bibliographic.php
@@ -8,6 +8,7 @@
 /**
  * @source https://www.iso.org/iso-639-language-codes.html
  * @source http://www.loc.gov/standards/iso639-2/php/code_list.php
+ * @standard ISO639_1
  */
 enum LanguageAlpha3Bibliographic: string
 {
diff --git a/src/Language/LanguageAlpha3Common.php b/src/Language/LanguageAlpha3Common.php
index 124f5f1..efc1e9e 100644
--- a/src/Language/LanguageAlpha3Common.php
+++ b/src/Language/LanguageAlpha3Common.php
@@ -8,6 +8,7 @@
 /**
  * @source https://www.iso.org/iso-639-language-codes.html
  * @source http://www.loc.gov/standards/iso639-2/php/code_list.php
+ * @standard ISO639_1
  */
 enum LanguageAlpha3Common: string
 {
diff --git a/src/Language/LanguageAlpha3Terminology.php b/src/Language/LanguageAlpha3Terminology.php
index b185481..4afbde1 100644
--- a/src/Language/LanguageAlpha3Terminology.php
+++ b/src/Language/LanguageAlpha3Terminology.php
@@ -8,6 +8,7 @@
 /**
  * @source https://www.iso.org/iso-639-language-codes.html
  * @source http://www.loc.gov/standards/iso639-2/php/code_list.php
+ * @standard ISO639_1
  */
 enum LanguageAlpha3Terminology: string
 {
diff --git a/src/Language/LanguageName.php b/src/Language/LanguageName.php
index cd9b69d..481bc3c 100644
--- a/src/Language/LanguageName.php
+++ b/src/Language/LanguageName.php
@@ -8,6 +8,7 @@
 /**
  * @source https://www.iso.org/iso-639-language-codes.html
  * @source http://www.loc.gov/standards/iso639-2/php/code_list.php
+ * @standard ISO639_1
  */
 enum LanguageName: string
 {