Complex sentence: Giroux started his career with a job with the Columbia Broadcasting System (CBS) in public relations, here after working for four years, he found his first editing job as a junior editor, at Harcourt, Brace & Company in 1940.
Split into simpler sentences: Giroux started his career with a job with the Columbia Broadcasting System (CBS) in public relations. After working there for four years, he found his first editing job as a junior editor, at Harcourt, Brace & Company in 1940.