That might be the suggested amount, and it is a great paper, but I think you are allowed to donate less if you choose: http://sci-hub.tw/10.1136/bmj.327.7429.14

That might be the suggested amount, and it is a great paper, but I think you are allowed to donate less if you choose: http://sci-hub.tw/10.1136/bmj.327.7429.1459 http://sci-hub.tw/10.1136/bmj.327.7429.1459