I am in Istanbul and I would like to buy or get the Lonely Planet guidebook of Turkey. Do you have any hint on where I can find it? Thanks
D&R Bookstores are located throughout Istanbul, and they generally stock Lonely Planet books in English - at least for the Istanbul and Turkey books.
They also have stores at the airport (airside) that definitely stock the English versions, however if you are already in Istanbul then this likely won't help you.
Istanbul's city centre is highly tourist-oriented, so I'd probably check book shops in Sultanahmet or on Istiklal street. I recall that there's a book shop right next to Sultanahmet tram station, in the same building as McDonalds; I definitely bought city maps in English there, not sure about Lonely Planet.
Amazon have a Kindle edition you can download and use with their app on your phone or tablet.
They have a paperback version too, if you can wait for delivery