READER'S DIGEST. (2004). READER'S DIGEST KNOWLEDGE QUEST: THE NATURAL WORLD. THE READER'S DIGEST ASSOCIATION LIMITED.
芝加哥风格引文READER'S DIGEST. READER'S DIGEST KNOWLEDGE QUEST: THE NATURAL WORLD. LONDON: THE READER'S DIGEST ASSOCIATION LIMITED, 2004.
MLA引文READER'S DIGEST. READER'S DIGEST KNOWLEDGE QUEST: THE NATURAL WORLD. THE READER'S DIGEST ASSOCIATION LIMITED, 2004.
警告：这些引文格式不一定是100％准确.