Get Reference to Parent Class

If you have a nested class inside a parent class, the 'this' keyword will of course refer to an instance of the nested class when used inside the nested class.  But is there any way to get a reference to an instance of the parent class, without passing one over to the constructor of the nested class?  

public class Parent
{
    class Nested
    {
        void doSomething()
        {
            Parent p = this; // <--- doesn't work because 'this' refers to an instance of Nested
        }
    }          
}

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