Ordering over Amazon

I just ordered a book on computer programming, Practical Qt, from Amazon. The thing is, I had to order it from Amazon in Germany (amazon.de), making as best use I could of my very rusty German (I took an A-level in the subject, but only got a D) to order a book which is published in Sweden and written in English (albeit by a German author). I was pretty sure that this book is in English, because the cover image is entirely in English, but I could not find this book either in the British or American Amazon sites. Nor could I find any way of changing the language on the German site. But I could log in with my user ID and password which I registered on the UK site. So if the German site knows about me, why doesn’t the English site know about English-language books available from Amazon in Germany?