People who have had professional experience working with children

People who have had professional experience working with children, such as teachers, nurses, are preferred.

교사, 간호사같이 아이들과 함께 일해 본 전문적인 경험이 있는 사람들이 선호된다.

여기서 professional experience working 이 부분이 문법적으로 이해가 안되요. Professional experience 하고 working 사이에 뭐가 생략되있는 건가요?????