“…For example, the direct sources originate in the financial system itself, such as the price information at various frequencies (Harris, 1986;Jain and Joh, 1988;Pan et al, 2017), the companies financial reports (Jones and Litzenberger, 1970;Zhou et al, 2015Zhou et al, , 2017a, and financial news (Geva and Zahavi, 2014;Li et al, 2014;Hagenau et al, 2013). The indirect sources are those outside the financial system, like the rise and fall of macro economic (Chen et al, 1986), the reactions and reflections from investors' emotion revealed by social media (Zhou et al, 2017b;Sun et al, 2017;Ruan et al, 2018;Zhang et al, 2017;Li et al, 2014), search engine (Preis et al, 2013) or analyst's recommendations (Duan et al, 2013), etc. The richness of data sources has provided the chances to understand the stock market more comprehensively and make the price prediction more accurate than before.…”