APA (7th ed.) Zitazioa
Schuller, R. H. (1980). The peak to peek principle. Doubleday & Co.
Chicago Style (17th ed.) Zitazioa
Schuller, Robert H. The Peak to Peek Principle. Garden City, New York: Doubleday & Co, 1980.
MLA (9th ed.) Zitazioa
Schuller, Robert H. The Peak to Peek Principle. Doubleday & Co, 1980.
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