The e-book was released Tuesday by HarperCollins. It also features a 1964 radio interview with Lee, who rarely speaks to the media. The regular e-book for "To Kill a Mockingbird," Lee's only novel, came out in July. She had been one of the last major authors to withhold electronic rights.
HarperCollins spokeswoman Tina Andreadis says the new "Mockingbird" edition had received 6,500 pre-orders, far more than for the usual "enhanced" book. She says the publisher has sold 80,000 copies of the regular e-book, a figure comparable to print sales. Total worldwide sales exceed 30 million copies since the book's 1960 release.
Both e-book editions are priced at $8.99.