Ejection of Double Knots from the Radio Core of PKS 1510–089 during the Strong Gamma-Ray Flares in 2015 by Park, Jongho, Lee, Sang-Sung, Kim, Jae-Young, Hodgson, Jeffrey A., Trippe, Sascha, Kim, Dae-Won, Algaba, Juan Carlos, Kino, Motoki, Zhao, Guang-Yao, Lee, Jee Won, Gurwell, Mark A.