Cita APA (7a ed.)

Gelpi, E. (1984). Lifelong education, opportunities and obstacles. [s.n.].

Cita Chicago Style (17a ed.)

Gelpi, Ettore. Lifelong Education, Opportunities and Obstacles. [S.l.]: [s.n.], 1984.

Cita MLA (9a ed.)

Gelpi, Ettore. Lifelong Education, Opportunities and Obstacles. [s.n.], 1984.