Added in-depth links for further reading to the state variable, function and function modifier overview in the structure section

docs/control-structures.rst

@@ -20,6 +20,8 @@ there is in C and JavaScript, so `if (1) { ... }` is *not* valid Solidity.
 
 .. index:: ! function;call, function;internal, function;external
 
+.. _function-calls:
+
 Function Calls
 ==============
 

docs/structure-of-a-contract.rst

@@ -25,6 +25,10 @@ State variables are values which are permanently stored in contract storage.
     // ...
   }
 
+See the :ref:`types` section for valid state variable types and
+:ref:`visibility-and-accessors` for possible choices for 
+visability.
+
 .. _functions:
 
 Functions
@@ -40,6 +44,10 @@ Functions are the executable units of code within a contract.
     }
   }
 
+Functions can be called internally or externally (:ref:`function-calls`)
+and have different levels of visibility (:ref:`visibility-and-accessors`)
+towards other contracts. 
+
 .. _function-modifiers:
 
 Function Modifiers
@@ -62,6 +70,8 @@ Function modifiers can be used to amend the semantics of functions in a declarat
     }
   }
 
+See :ref:`modifiers` in the section on contracts for a more in-depth explanation.
+
 .. _events:
 
 Events

docs/types.rst

@@ -1,5 +1,7 @@
 .. index:: type
 
+.. _types:
+
 *****
 Types
 *****