This is sort of an intriguing topic, because, depending on the story, he/she can and will reveal the source.

First of all: a good journalist must always confirm a story from three primary sources – that is the best case scenario, the fact that you actually have three, independent from each other – so no shared information per se.

Secondly: depending of the topic of the story, he/she should reveal the sources – for example, when you present news and interpret them or analyze facts, you are supposed to reveal the sources, because it acts as a Bibliography. If the news is something affecting integrity of individuals, best is NOT to reveal them. Let’s say you stumbled upon a big case and you start to investigate: some senator did something – it is recommended to protect your sources as much as possible – otherwise you will end up with dead informers 🙂 Therefore jeopardizing a potential law suit where your informer was supposed to testify.

The laws of ethic journalism specifically state to never reveal your sources, unless the case is safe to do so (read above why and when).