GuruNet, an online reference search engine that has been searching for the right revenue model again changed, moving to an advertising model as the prospects of online advertising continue to grow. After having experimented with lifetime licensing, GuruNet had been charging about $30 per year for individual users of its querying service. An executive noted that it was becoming harder and harder to charge for content that is increasingly found free online. Google in particular has been gunning for the academic and reference market, recently releasing a scholarly version of its ubiquitous search engine.