The three volumes of basic articles are all basic knowledge of postgraduate entrance examination, and their understanding of knowledge points is the same. There is no difference. You can choose to buy according to your own needs.
The basic part is universal, but it is impossible to improve the part. First, the number two is particularly deep, and the number three is out of reach. Secondly, the physical application of number two, the application of definite integral geometry and the order reduction of differential equations are not available.