Which famous book series had its initial marketing campaign strictly limited to school book fairs and word-of-mouth, with no traditional advertising, as a deliberate strategy by the publisher?

Throughout history, publishing houses have created innovative and memorable advertising campaigns to promote literary works. Some of these campaigns revolutionized book marketing, turning novels into cultural phenomena and household names. This trivia question explores one of the most influential book promotion campaigns of the early 21st century that changed how literature was marketed to the public.

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Harry Potter series by J.K. Rowling
The Hunger Games trilogy by Suzanne Collins
A Series of Unfortunate Events by Lemony Snicket
Percy Jackson & the Olympians by Rick Riordan