Cita APA (7a ed.)

(1968). The 1968 World Book Year Book. Field Enterprises Educational Corporation.

Cita Chicago Style (17a ed.)

The 1968 World Book Year Book. Chicago, Estados Unidos: Field Enterprises Educational Corporation, 1968.

Cita MLA (9a ed.)

The 1968 World Book Year Book. Field Enterprises Educational Corporation, 1968.