A Course of Probability Theory and Mathematical Statistics edited by Yan, Cheng and Pu Xiaolong Higher Education Press; Application of Multivariate Statistical Analysis in Peking University Publishing House, edited by Gao Huixuan: Linear Statistical Model, edited by Wang Songgui, Chen Min and Chen Liping, Higher Education Press. I am also a math major. The books listed above are for reference only. Relatively speaking, it's classic. Can be combined with related software to learn. Learn roughly first, and then study deeply and carefully. I believe it will be beneficial, hehe.