READER'S DIGEST. (2004). READER'S DIGEST KNOWLEDGE QUEST: THE NATURAL WORLD. THE READER'S DIGEST ASSOCIATION LIMITED.
Chicago-referens (17:e uppl.)READER'S DIGEST. READER'S DIGEST KNOWLEDGE QUEST: THE NATURAL WORLD. LONDON: THE READER'S DIGEST ASSOCIATION LIMITED, 2004.
MLA-referens (9:e uppl.)READER'S DIGEST. READER'S DIGEST KNOWLEDGE QUEST: THE NATURAL WORLD. THE READER'S DIGEST ASSOCIATION LIMITED, 2004.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.