Before you start your research, it is important to understand the information cycle. When a noteworthy event occurs, it will first appear online (web-based news, twitter, facebook, etc.) and on the radio and television news. The next day, it will appear in print newspapers. Over the next week or so, it will be mentioned in print magazines. Several weeks or months later, scholarly journal articles may cover this topic. Many months or even years later, the event will be in printed books. Several years after that, it will appear in print reference books.
If the topic or event you are researching has occurred recently, you likely will not find information in a print book; however, newspaper or magazine articles may cover it. If you are researching a historical event, scholarly journal articles or books may be a better fit.