Library genesis is the best thing that happened to research since Google (and a huge number of researchers use it, secretly). Being able to access any obscure technical book in the world in a few seconds is literally orders of magnitude more efficient than waiting a week for an interlibrary loan. I dread the day it inevitably gets shut down due to pressure from the copyright mafia. It's ridiculous that such a service isn't 1) legal, and 2) publicly funded (with due compensation to the authors).