In general we don't use articles (a/an, the) in newspaper and magazine headlines, but they can be included. Often we give students who study English a task of rewriting headlines and expect students to remove articles, but it is not obligatory. In the real world newspaper and magazine editors do whatever they like (they don't have to pass an exam), so you can find examples where articles are used. In The Times recently one headline was "Prince issues Gaza plea for a permanent peace." - I think it would have be fine without the article "a", so I am not sure why they decided to include it. Perhaps it just looked better on the page layout?