sci
hub

to open science
Sellamuthu, Harishkumar; Sharma, Ram Krishan . (2016). Orbit Theory with Lunar Perturbation in Terms of Kustaanheimo–Stiefel Regular Elements. Journal of Guidance, Control, and Dynamics, (), 1–6. doi:10.2514/1.G002342 
An interview with Sci-Hub Founder Alexandra Elbakyan,Who exactly should pay for academic research