"I read harder books that I can't understand right now."

I never read such a hard book before.

It makes available the big awkward hard to find and prohibitively expensive books.

It's the hardest book to read and I know it drives people crazy.

No way I'm paying anywhere near the "normal" price for a hard book.

But financial pressures are making economically marginal books increasingly hard to justify.

It is at the heart of the town and the owners are so knowledgeable they making looking for a hard to find book so easy.

This is a rather unusual book, very well written and hard to put down.

Many children happily tackle much harder books than usual if they are interested in the subject.

That must have been a hard book to come across.