Second, when we use the features from only one external resource, the results from some resources are competitive compared to that from the system using internal features.
second, to estimate the bigrams' weights, in addition to using information from the test documents, such as document frequency, syntactic role in a sentence, etc., we utilize a variety of external resources, including a corpus of news articles with human generated summaries, Wiki documents, description of name entities from DBpedia, WordNet, and sentiWordNet.