context: Survivors is a children's novel series written by a team of authors under the pseudonym Erin Hunter, who also wrote the Warriors series. Survivors follows the adventures of a group of pet dogs who form a pack with the help of Lucky, a lone dog, after an earthquake separates them from their owners. The first book The Empty City was released on 21 August 2012, and was followed by A Hidden Enemy on 7 May 2013, Darkness Falls on 3 September 2013, The Broken Path on 11 February 2014, The Endless Lake on 3 June 2014, and Storm of Dogs released on 10 February 2015.
question: When was the first Survivors novel published?
answers.text: 21 August 2012 21 August 2012 21 August 2012