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M. Ebrahimzadeh; P.J. Phillips; S. Das. (2001). Low-threshold mid-infrared optical parametric oscillation in periodically poled LiNbO3 synchronously pumped by a Ti:sapphire laser. , 72(7), 793–801. doi:10.1007/s003400100559 
An interview with Sci-Hub Founder Alexandra Elbakyan,Who exactly should pay for academic research