EUROPA PUBLICATIONS LIMITDE. (1977). The world of learning 1977- 78 (ed.28.). Europa Publications limited.
Чикаго-гийн эшлэл (17 дахь хэвлэлт)EUROPA PUBLICATIONS LIMITDE. The World of Learning 1977- 78. ed.28. London: Europa Publications limited, 1977.
MLA -ийн эшлэл (9 дэх хэвлэлт)EUROPA PUBLICATIONS LIMITDE. The World of Learning 1977- 78. ed.28. Europa Publications limited, 1977.