Liu was Liu Gongquan, a calligrapher in Tang Dynasty, Zhao was Zhao Mengfu, a calligrapher in Yuan Dynasty, and Ou was a calligrapher in Tang Dynasty. Yan Jin and Liu Gu are desirable, while Europe and Zhao each have their own strengths. Learn these four schools first, and then learn Wang's running script. Calligraphers often say that models are standing, lines are walking and grass is flying. Learn to stand before you go, but you can't learn to stand first, but you can learn all of them.