sentence1: In 1956 , she worked with the orchestras of Boris Simeonov and Emil Georgiev for Big Orchestra Concert Directorate conductors , who were Christo Vuchkov and Dimitar Ganev .
sentence2: In 1956 , she worked with the orchestras of Boris Simeonov and Emil Georgiev for Big Orchestra Concert Directorate conductors of which were Christo Vuchkov and Dimitar Ganev .