Hi Hakim
Yes, you can certainly buy them. The GM repertoire books are by GMs and certainly intended for GM readers, however the books are written in such a way that us mortals can choose how far we wish to delve into the details on show (and the books are very detailed).
The motto behind the GM repertoire series is that there is a lot of benefit to be had studying main lines because they are main lines for a reason: they are 100% sound - based on good moves/ideas - and lead to good positions. Good positions, based on understanding, will give better results.
Quality have also published other excellent books. I thoroughly recommend the book "Rook versus Two Minor Pieces" by Esben Lund. It will teach you all the ins and outs of that material imbalance; it is based on training material by Esben (who uses Silas as his first name now, btw).
Of course, Jacob Aagaard is an old friend so I guess I would push his company. Seriously, though -- he and John Shaw are really scrupulous in producing the best books possible. In short Quality!
Their website is also an important resource.
http://www.qualitychess.co.uk/
Good Morning All
i'm wondering if quality chess books (especially GM repertoire) are for intermediate chess player (1600-1900)
http://www.qualitychess.co.uk/