1. My initial idea was that only e-book is not a good idea To eBook or not to eBook?

2. Statistics I found on web changed my opinion To eBook or not to eBook?

3. The New York Times E-Books Outsell Print Books at Amazon - Published: May 19, 2011 http://www.nytimes.com/2011/05/20/technology/20amazon.html?_r=0 E-book sales in March were $69 million, an increase of 146 percent from the year before, the Association of American Publishers. To eBook or not to eBook?

4. BBC.com Amazon selling more Kindle ebooks than print books - 6 August 2012 The UK's biggest book retailer Amazon now sells more ebooks than hardbacks and paperbacks combined, the company has said. http://www.bbc.com/news/technology-19148146 For every 100 print books sold through the site, Amazon said it sold 114 titles for its Kindle e-reader device To eBook or not to eBook?

5. US TODAY E-book sales are up 43%, but that's still a 'slowdown' http://www.usatoday.com/story/life/books/2013/05/15/e-book-sales/2159117/ To eBook or not to eBook? Preliminary data from the annual BookStats study by the Association of American Publishers and the Book Industry Study Group, shows that 457 million e-books were sold last year. That's up 4456% since 2008, when just 10 million e-books were sold. But why the increase was less than previous years is up to interpretation.

6. To eBook or not to eBook? http://www.businessinsider.com/chart-of-the-day-e-books-versus-print-books-2012-4

7. To eBook or not to eBook? https://bepp.wharton.upenn.edu/bepp/assets/File/HuiLi_ebook_Feb15.pdf