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3. Twitter statistics, https://www.internetlivestats.com/twitter-statistics/.
4. Sentiment analysis and opinion mining;Liu;Synth. Lect. Hum. Lang. Technol.,2012
5. Emotion Recognition and Sentiment Analysis Market, https://www.tractica.com/newsroom/press-releases/emotion-recognition-and-sentiment-analysis-market-to-reach-3-8-billion-by-2025/.