Systems and methods for rendering automatic annotation for electronic books with external information provided by an information database. A computer implemented method is used to automatically determine key terms and match the key terms with correct information from external information sources for presentation at an e-book page. The key terms can be detected based on a TF-IDF based content analysis process. The detected key terms can be processed by a disambiguation process to select the pertinent definition for multi-sense terms according to one or more selected information sources. Hyperlinks can be embedded in the key terms for direct and convenient link to the matching external information in response to user interactions.
