diff --git a/articles/abstract_syntax_tree.md b/articles/abstract_syntax_tree.md
index 74bbfe3..4cf96f8 100644
--- a/articles/abstract_syntax_tree.md
+++ b/articles/abstract_syntax_tree.md
@@ -6,9 +6,10 @@ concrete syntax tree.
 
 An AST is the first [intermediate representation](intermediate_representation.md) used
 by a programming language, being created by a [parser](parser.md). Usually this tree is
-later decorated with additional information by the compiler, such as typing information.
+later decorated with additional information by the compiler, such as typing information in latter compilation
+phases, in this case the semantic analysis phase.
 
-[Lisp](lisp.md) famously uses a very simple syntax for its source code, (S-Expressions)(sexpression.md), which makes
+[Lisp](lisp.md) famously uses a very simple syntax for its source code, [S-Expressions](sexpression.md), which makes
 the AST evident and makes Lisp [homoiconic](homoiconic.md).
 
 For this C function that calculates the factorial of *n*: