65438+February 2022. As of June 27th, 2023, according to Li Yanfang 900 Questions, Li Yanfang 900 Questions was published in February, 2022. Li Yanfang's Handbook of Mathematical Formulas for Postgraduate Entrance Examination contains 900 formula theorems, knowledge maps, definition theorems, classical conclusions and common methods. It can reduce the burden and improve the speed of doing problems.