Bests & Worsts Reviews from Amazon

I have purchased, assembled and used a number of Sauder products over the years and have been very satisfied with the ease of assembly and quality. However, after a little over a year of using this bookcase to store books, the top two shelves have warped and the pieces beginning to separate so that in order to continue to use it I had to turn over the shelves (unattractive) so that the weight of the books would warp the shelves back to flat once again. We live in a northern midwest state - we have air conditioning in the summer and heat in the winter so I don't think it's an environmental issue - I simply think that the particle board or MDF or whatever the shelves are made of is simply not strong enough to support full shelves of real books. My books are a combination of hard cover and paperback. The third picture from the left shows how I turned the shelf over to 'fix' the problem.