Why is Wanbao Encyclopedia so accurate?

This is an encyclopedia. According to the relevant information of Guangming. Wanbao is an encyclopedia, so it is so accurate. Wanbao is an encyclopedia with more than 700 pages, covering yin and yang, five elements, astronomy and geography, divination and geomantic omen, calligraphy and painting of piano and chess, and records of Korea, Ryukyu and Japan.