The core shift measurements for two-sided jets affected by Free-Free absorption using VLBATakafumi Haga, Akihiro Doi, Yasuhiro Murata, Hiroshi Sudou, Seiji Kameno, Kazuhiro Hada and Hiroshi NagaiEPJ Web of Conferences, 61 (2013) 08004DOI: https://doi.org/10.1051/epjconf/20136108004