In this paper, we present a study about the most popular information sources available on the Web (e.g., Google, Facebook, Twitter) and the available methods to verify their publications. We propose a generic credibility analysis model for social information sources, which is instantiated for Twitter. We show a proof of concepts through the development of World White Web, a Google Chrome extension application that implements the model to analyze tweets in real time, using web scraping. Our study demonstrates the feasibility and suitability of creating efficient methods to analyze the credibility of publication on social networks and points out the challenges and open problems that should be overcome in future solutions in this area.