Investment Approach by Alpha Value: Case of Firms Listed on the Stock Market in Vietnam Period Before and After the Covid-19 Pandemic. - Anh Phong Nguyen; Huyen Linh Dang; Thi-Tra-My Nguyen; Hoang Nam Cao; Ha Nam Phuong Nguyen; Huynh Phuong Vy Nguyen (MMBD, 2022)