Cita APA (7a ed.)

Onnis, L. (1990). A systemic approach to the concept of crisis. [s.n.].

Cita Chicago Style (17a ed.)

Onnis, Luigi. A Systemic Approach to the Concept of Crisis. [S.l.]: [s.n.], 1990.

Cita MLA (9a ed.)

Onnis, Luigi. A Systemic Approach to the Concept of Crisis. [s.n.], 1990.