One of the main goals of the e.t.s.v. Thor is to provide good study material for the students of the department of Electrical Engineering. One part of this is selling study books at a discounted price. This discount only counts when you are a Thor member, which comes at the one-time cost of €25 (way less than the discount!) and gives you a lot of other advantages too.
You can always order your discount books here: https://wo4you.nl/.
Also, for each quartile there is a period where you can order the books that are in our book list with a discount of 17%. For Quartile 1 that period has started!