You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
United_States_presidential_election,_2004

Context:
During August and September 2004, there was an intense focus on events that occurred in the late 1960s and early 1970s. Bush was accused of failing to fulfill his required service in the Texas Air National Guard. However, the focus quickly shifted to the conduct of CBS News after they aired a segment on 60 Minutes Wednesday introducing what became known as the Killian documents. Serious doubts about the documents' authenticity quickly emerged, leading CBS to appoint a review panel that eventually resulted in the firing of the news producer and other significant staffing changes.

Question:
Which news agency came under review resulting in the firing of their producer?

CBS News