Recommend some math books of the department of mathematics ~ introductory and advanced.
Qiu's Advanced Algebra of Peking University is rich and detailed, which explains the abstract thought of linear space with the idea of dissecting sparrows. There is also Xie Huimin's Lecture Notes on Mathematical Analysis Exercises, which is really a good book for learning and analyzing, and Fichkin Goelz's Calculus Course, which must be read by people majoring in mathematics. Brush Jimidovich ~ \(≧▽≦)/~ more if you have nothing to do!