There is this book by Tony Grice. It's a invaluable badminton book, for beginners, students, amateurs and advanced players alike.
Another resource that is valuable is the badminton bible created by "Gollum" aka Mike Hopley from England.
Speaking of England, I think they are pretty strong in the doubles and mixed doubles, but slightly weaker in the singles department amongst the European countries.
However, the renaissance in England's fortune in doubles can be partly be attributed to Rexy Maniaky's stint as a coach there. Now with the aging Clark, Robertson, Emms and Kellogg, England is sorely lacking in a new talent, when every talented young lad wants to play for Manchester United, Liverpool, etc. Badminton is an expensive sport that doesn't pay well. No wonder, the lure of Old Trafford is so strong in England.
Sad, considering England invented Badminton and host the prestigious All-England open at Birmigham.
Denmark is still the powerhouse of Europe.