Cita APA (7a ed.)

Engel, G. L. (1977). The need for a new medical model: A challenge for biomedicine. [s.n.].

Cita Chicago Style (17a ed.)

Engel, George L. The Need for a New Medical Model: A Challenge for Biomedicine. [S.l.]: [s.n.], 1977.

Cita MLA (9a ed.)

Engel, George L. The Need for a New Medical Model: A Challenge for Biomedicine. [s.n.], 1977.