In a country like Indonesia where the cost of these sorts of text books is very burdensome, it seems perverse to require parents to expend hundreds of dollars when perfectly acceptable, free alternatives are available. Admittedly, the books are not paper copies but it would still be cheaper to ask parents to buy a cheap tablet on which to read the ebooks. One advantage is that students would then not have to lug around heavy textbooks in their backpacks.
Nonetheless, it is useful to me because I found a number of A level Mathematics textbooks that I've now downloaded and added to my already extensive collection of e-textbooks. For example, this advanced level Statistics textbook should be helpful as I'm currently embarked on a revision of this topic.
