APA-ийн эшлэл(7 дахь хэвлэлт)

Reichheld, F. F. (2006). The ultimate question: Driving good profits and true growth (NA.). Harvard Business School Press.

Чикаго-гийн эшлэл (17 дахь хэвлэлт)

Reichheld, Frederick F. The Ultimate Question: Driving Good Profits and True Growth. NA. USA: Harvard Business School Press, 2006.

MLA -ийн эшлэл (9 дэх хэвлэлт)

Reichheld, Frederick F. The Ultimate Question: Driving Good Profits and True Growth. NA. Harvard Business School Press, 2006.