What are the necessary basic books for learning Feng Shui?

In addition to easy-to-learn books, there are three professional books: Luan Tou, Li Qi and Choosing a Day.

You can look at Xue Xinfu first.

Li Qi has many schools and books. Eight Houses Mirror, Three Essentials of Yang House, Shen Shi Metaphysics, Geographical Dialectics and so on.

Japanese classics such as jade sagger, kiln, purlin, Xie Fangshu, etc. There are more folk secrets.