Amazon calculates a product's star ratings based on a machine learned model instead of a raw data average. The model takes into account factors including the age of a rating, whether the ratings are from verified purchasers and factors that establish reviewer trustworthiness.
Pirated. Poor quality pages. Gray, very thin pages that show the printing on the other side of the page as well. Not worth paying for original and getting this. Wish I had got this from an offline store.