1. The many facets of the cause–effect relation;Khoo,2002
2. An Abstract of a Treatise of Human Nature;Hume,1938
3. Concepts, Kinds, and Cognitive Development;Keil,1992
4. Cause and effect in science textbooks;Darian,1996
5. Expressing causation in written English;Xuelan;RELC Journal,1992