Important redology books include Wang Guowei's Comments on A Dream of Red Mansions, Cai Yuanpei's Research on A Dream of Red Mansions, Hu Shi's Textual Research on A Dream of Red Mansions, and Zhou's New Evidence of A Dream of Red Mansions, but they are not suitable for beginners to read.
I suggest you look at Lin's Dream of Red Mansions, Wang Kunlun's Dream of Red Mansions, Yu Pingbo's Dream of Red Mansions, and Appreciation of Poems and Songs of A Dream of Red Mansions, all of which are important research works.