1. A method for identifying documents referring to an entity, the entity being associated with a first set of features, the method comprising: identifying a first set of documents based on a first model and the first set of features, the first set of documents each comprising a sufficient number of features in common with the first set of features to identify a document referring to the entity according to the first model; determining a second model based on the features of the first set of documents; and identifying a second set of documents based on the second model and the first set of features, the second set of documents each comprising a sufficient number of features in common with the first set of features to identify a document referring to the entity according to the second model.