Preston, P. W. (1982). Theories of development. Routledge & Kegan Paul.
Cita Chicago (17th ed.)Preston, P. W. Theories of Development. London: Routledge & Kegan Paul, 1982.
Cita MLA (9th ed.)Preston, P. W. Theories of Development. Routledge & Kegan Paul, 1982.
Atenció: Aquestes cites poden no estar 100% correctes.