APA-ийн эшлэл(7 дахь хэвлэлт)

Babbage, K. J. (2010). The extreme principle: What matters most, what works best. Rowman & Littlefield Education.

Чикаго-гийн эшлэл (17 дахь хэвлэлт)

Babbage, Keen J. The Extreme Principle: What Matters Most, What Works Best. Lanham: Rowman & Littlefield Education, 2010.

MLA -ийн эшлэл (9 дэх хэвлэлт)

Babbage, Keen J. The Extreme Principle: What Matters Most, What Works Best. Rowman & Littlefield Education, 2010.