Need help with calling functions (Inheritance hierarchy)

[K Nev]

Okay so I have an Inheritance hierarchy and I need help with one of my classes. I have a class called LINKED_LIST and a class called STACK. STACK's functions need to called from LINKED_LIST, but I cant figure out what to do.

Here is my LINKED_LIST.h file

#ifndef LINKED_LIST_H
#define LINKED_LIST_H
#include "ORDERED_COLLECTION.h"
#include "NODE.h"
template <class T>
class LINKED_LIST: public ORDERED_COLLECTION<T>
{
  public:
    LINKED_LIST(): m_head(NULL),m_tail(NULL) {}
    LINKED_LIST(const LINKED_LIST<T>& cpy):
        m_head(NULL),m_tail(NULL) {*this = cpy;}
    ~LINKED_LIST() { clear(); }
    void insertAtHead(const T& ins);
    void insertAtTail(const T& ins);
    void removeAtHead();
    void removeAtTail();
    bool find(const T& f) const;
    bool removeFirstOccurrence(const T& rem);
    unsigned int removeAllOccurrences(const T& rem);
    void clear();
    LINKED_LIST<T>& operator=(const LINKED_LIST<T>& rhs);
    bool operator== (const LINKED_LIST<T>& rhs) const;
    NODE<T>* getHeadPtr() {return m_head;}
    NODE<T>* getTailPtr() {return m_tail;}
	
  protected:
    NODE<T>* m_head, *m_tail;
};
#include "LINKED_LIST.hpp"
#endif 

and here is my STACK.h code

#ifndef STACK_H
#define STACK_H

#include "LINKED_LIST.h"

template <class T>
class STACK : protected LINKED_LIST<T>
{
 public:
   
  const T& top(); // needs to call NODE<T>* getHeadPtr() {return m_head;}
  void push(const T& ins); // needs to call void InserteAtHead();
  void pop(); // needs to call void removeAtHead();
  LINKED_LIST<T>& operator=(const LINKED_LIST<T>& rhs); //works fine
  bool operator== (const LINKED_LIST<T>& rhs) const; // works fine

};

#endif 

I'm not sure how I use top to call getHeadPtr