Dev - C++ - Por que me sale este error en un proyecto de C++

///clase Student

#ifndef STUDENT_H_INCLUDED

#define STUDENT_H_INCLUDED

#include<iostream>

#include<string>

#include "name.h"

#include "data.h"

#include "SubjectList.h"

using namespace std;

class Student {

    private:

        std::string code;

        Name name;

        Date dataOfBirth;

        std::string career;

        Date dateOfAdmission;

        float grade;

        SubjectList subjectList; ///instancia de clase

    public:

        Student();

        Student(const Student&);

        std::string getCode();

        Name getName();

        Date getDateOfBirth();

        std::string getCareer();

        Date getDateOfAdmission();

        float getGrade();

        SubjectList& getSubjectList();

        void setCode(const std::string&);

        void setName(const Name&);

        void setDateOfBirth(const Date&);

        void setCareer(const std::string&);

        void setDateOfAdmission(const Date&);

        void setGrade(const float&);

        void setSubjectList(const SubjectList&);

        std::string toString(bool);

        void writeToDisk(const std::string&);

        void readFromDisk(const std::string&);

        Student& operator = (const Student&);

        bool operator == (Student&);

        friend std::ostream& operator << (std::ostream&, Student&);

        friend std::istream& operator >> (std::istream&, Student&);

    };

#endif // STUDENT_H_INCLUDED

///clase StudentNode

#ifndef STUDENTNODE_H_INCLUDED

#define STUDENTNODE_H_INCLUDED

#include "student.h"

class StudentNode {

    private:

        Student *dataPtr;

        StudentNode *prev;

        StudentNode *next;

    public:

        StudentNode();

        StudentNode(const Student&);

        Student *getDataPtr();

        Student& getData();

        StudentNode *getPrev();

        StudentNode *getNext();

        void setDataPtr(const Student*);

        void setData(const Student&);

        void setPrev(StudentNode*);

        void setNext(StudentNode*);

    };

#endif // STUDENTNODE_H_INCLUDED