Empirical Study of Machine Learning Based Approach for Opinion Mining in Tweets. - Grigori Sidorov; Sabino Miranda-Jiménez; Francisco Viveros Jiménez; Alexander F. Gelbukh; Noé Alejandro Castro-Sánchez; Francisco Velasquez; Ismael Díaz-Rangel; Sergio Suárez Guerra; Alejandro Treviño; Juan Gordon (MICAI (1), 2012)