... Methods in Natural Language Processing, Sapporo Sarmento, Luís, Paula Carvalho, Mário J Silva, and Eugénio Oliveira 2009 “Automatic creation of a reference corpus for political opinion mining in usergenerated ... 2005 “Annotating expressions of opinions and emotions in language” In Language Resources and Evaluation, volume 39, 2-3 We are grateful to João Ramalho for his assistance in the annotation of SentiCorpus-PT ... 2007 “Crystal: Analyzing predictive opinions on the web” In Proc of the Joint Conference on Empirical Methods in Natural Language Processing and Computational Natural Language Learning, Prague Krippendorff,...