Currently the biggest ebook reader is the Sony 13.3 incher but it is hard to obtain and quite expensive: http://the-digital-reader.com/2014/03/27/sonys-13-3-ereader-...
Thanks for the hint. Maybe I should buy that one, before Sony stops producing eBook readers.
On February 6, 2014, Sony announced that it is closing its North American Reader Store in late March, migrating all its customers to the Kobo Reader Store.
-- http://en.wikipedia.org/wiki/Sony_Reader#Models_and_availabi...
I hate the eye-strain that the iPad causes when I use it outside in nature. Sometimes I go back to my Kindle, but it is too slow and too small for my complex PDFs.