Cita APA (7th ed.)
(1971). The WORLD of learning: 1.970-71 (21a. ed.). Europa Publications Limited.
Cita Chicago (17th ed.)
The WORLD of Learning: 1.970-71. 21a. ed. England: Europa Publications Limited, 1971.
Cita MLA (9th ed.)
The WORLD of Learning: 1.970-71. 21a. ed. Europa Publications Limited, 1971.
Atenció: Aquestes cites poden no estar 100% correctes.