I think providing only the used sources is enough and the journalist should do all what is reasonable possible to find the original source of a news, so avoid s

I think providing only the used sources is enough and the journalist should do all what is reasonable possible to find the original source of a news, so avoid speaking about something they read/heard from X and X said he read/seen from Y and Y from Z , the journalist should try to find the original source(if possible). For things that should remain anonymous they should describe how credible is the source and content.