sci
hub

to open science
Patterson, Michael A.; Rao, Anil . (2012). Exploiting Sparsity in Direct Collocation Pseudospectral Methods for Solving Optimal Control Problems. Journal of Spacecraft and Rockets, 49(2), 354–377. doi:10.2514/1.56741 
An interview with Sci-Hub Founder Alexandra Elbakyan,Who exactly should pay for academic research