BIG ELEPHANT FOUNDATION. (2012). MIND TWISTER MATHS OLYMPIAD WORKBOOK- 2. BIG ELEPHANT FOUNDATION.
芝加哥风格引文BIG ELEPHANT FOUNDATION. MIND TWISTER MATHS OLYMPIAD WORKBOOK- 2. BIG ELEPHANT FOUNDATION, 2012.
MLA引文BIG ELEPHANT FOUNDATION. MIND TWISTER MATHS OLYMPIAD WORKBOOK- 2. BIG ELEPHANT FOUNDATION, 2012.
警告：这些引文格式不一定是100％准确.