Add reference for ISO 8859-1

files/en-us/web/javascript/guide/grammar_and_types/index.md

@@ -77,7 +77,7 @@ You use variables as symbolic names for values in your application. The names of
 
 A JavaScript identifier usually starts with a letter, underscore (`_`), or dollar sign (`$`). Subsequent characters can also be digits (`0` – `9`). Because JavaScript is case sensitive, letters include the characters `A` through `Z` (uppercase) as well as `a` through `z` (lowercase).
 
-You can use most of ISO 8859-1 or Unicode letters such as `å` and `ü` in identifiers. (For more details, see [this blog post](https://mathiasbynens.be/notes/javascript-identifiers-es6) or the [lexical grammar](/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#identifiers) reference.) You can also use the [Unicode escape sequences](/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#string_literals) as characters in identifiers.
+You can use most of [ISO 8859-1](https://en.wikipedia.org/wiki/ISO/IEC_8859-1) or Unicode letters such as `å` and `ü` in identifiers. (For more details, see [this blog post](https://mathiasbynens.be/notes/javascript-identifiers-es6) or the [lexical grammar](/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#identifiers) reference.) You can also use the [Unicode escape sequences](/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#string_literals) as characters in identifiers.
 
 Some examples of legal names are `Number_hits`, `temp99`, `$credit`, and `_name`.