In the six months since the launch of Kindle Singles, Amazon's newest venture into short-form digital content, the e-tailer has published 75 titles to the platform and has worked to distinguish Singles titles from regular Kindle titles by making them part of a carefully selected catalogue.

Unlike Kindle Direct Publishing, which allows any rights holder to publish a book to the Kindle Store, Kindle Singles submissions are sent to an e-mail address where they are reviewed by David Blum, the Kindle Singles editor. If accepted, Blum works with the author to develop the content for publication. It is this extra editorial step that can take posting a Kindle Singles as long as two weeks, while a KDP book can be published in a matter of hours. An Amazon spokesperson called Kindle Singles "a highly curated platform."

Singles titles range from fiction from traditional publishing houses, such as David Baldacci's "No Time Left," published by his print house, Grand Central Publishing, to Tim Gunn's nonfiction piece "Shaken, Not Stirred," which the author published himself. Singles bestsellers include "Three Cups of Deceit" by Jon Krakauer, published by Byliner, the long-form journalism Web site, and Jodi Picoult's "Leaving Home: Short Pieces," with her agent, the Laura Gross Literary Agency, serving as the publisher.

Although Amazon declined to discuss sales figures (and author/publishers sign nondisclosure agreements as part of the Singles program), the e-tailer said six Singles titles have broken into the Top 20 bestselling titles in the Kindle Store, which includes all Kindle books.

Amazon is adding about three titles to the Singles catalogue every week, and as the number of quality submissions increases, Amazon expects that number to go up.

Kindle Singles, which run between 5,000 and 30,000 words, are priced from 99 cents to $4.99, and the typical publisher/Amazon split is 70/30.