diff --git a/HTMLKit/CSSNthExpressionParser.h b/HTMLKit/CSSNthExpressionParser.h
index 5323282..e99de22 100644
--- a/HTMLKit/CSSNthExpressionParser.h
+++ b/HTMLKit/CSSNthExpressionParser.h
@@ -11,8 +11,19 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
+/**
+ The Nth-Expression Parser.
+
+ Parses CSS nth-expressions, e.g. '-2n+3', 'odd', ...etc.
+ */
 @interface CSSNthExpressionParser : NSObject
 
+/**
+ Parses a CSS nth-exrepssion string.
+
+ @param expression The expression string to parse.
+ @see CSSNthExpression
+ */
 + (CSSNthExpression)parseExpression:(NSString *)expression;
 
 @end
diff --git a/HTMLKit/CSSSelectorParser.h b/HTMLKit/CSSSelectorParser.h
index 3f4fca4..15bdd9f 100644
--- a/HTMLKit/CSSSelectorParser.h
+++ b/HTMLKit/CSSSelectorParser.h
@@ -12,8 +12,23 @@ NS_ASSUME_NONNULL_BEGIN
 
 @class CSSSelector;
 
+/**
+ The CSS Selectors Parser.
+
+ Parses CSS Level 3 Selectors:
+ http://www.w3.org/TR/css3-selectors/
+ */
 @interface CSSSelectorParser : NSObject
 
+/**
+ Parses a CSS3 selector string.
+
+ @param string The CSS3 selector string.
+ @param error If an error occurs, upon return contains an `NSError` object that describes the problem.
+ @returns A parsed CSSSelector, `nil` if an error occurred.
+
+ @see CSSelector
+ */
 + (CSSSelector *)parseSelector:(NSString *)string error:(NSError **)error;
 
 @end