Cita APA (7th ed.)
Ginsburg, H., & Opper, S. (1969). Piaget's theory of intellectual development: An introd. Prentice Hall.
Cita Chicago (17th ed.)
Ginsburg, Herbert, i Sylvia Opper. Piaget's Theory of Intellectual Development: An Introd. Englewood cliffs, USA: Prentice Hall, 1969.
Cita MLA (9th ed.)
Ginsburg, Herbert, i Sylvia Opper. Piaget's Theory of Intellectual Development: An Introd. Prentice Hall, 1969.
Atenció: Aquestes cites poden no estar 100% correctes.