Amazon.com (AMZN) announced on Thursday it agreed to acquire Goodreads, a website that readers use to give book reviews and recommendations.

The online retail giant did not disclose financial terms of the deal, which is expected to close in the second quarter. Following the acquisition, Goodreads’ headquarters will remain in San Francisco.

Goodreads, which was launched in 2007, has more than 16 million members and 30,000 virtual book clubs on the site. Amazon noted that in the last 90 days, Goodreads members have added more than four books per second to their “want to read” shelves.

“Both Amazon and Goodreads have helped thousands of authors reach a wider audience and make a better living at their craft,” Russ Grandinetti, Amazon’s Vice President of Kindle Content, said in a statement. “Together we intend to build many new ways to delight readers and authors alike.”

Goodreads co-founder and CEO Otis Chandler said the combination with Amazon’s Kindle will allow Goodreads to “move faster in bringing the Goodreads experience” to readers.

Amazon shares were down 29 cents to $266.20 in after-hours trading.

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