EUROPA PUBLICATIONS LTDA. (1997). The world of learning 1998 (ed.48.). Europa Publications limited.
Чикаго-гийн эшлэл (17 дахь хэвлэлт)EUROPA PUBLICATIONS LTDA. The World of Learning 1998. ed.48. London: Europa Publications limited, 1997.
MLA -ийн эшлэл (9 дэх хэвлэлт)EUROPA PUBLICATIONS LTDA. The World of Learning 1998. ed.48. Europa Publications limited, 1997.