Ancient times:
Du Gongbu Collection edited by Wang Zhu in the Northern Song Dynasty;
Yang Qing Lun notes Du Shi Jing Quan;
"Zhu Qian Du Fu's Poems", by Qian Qing and Qian Yi;
Du Shi, edited by Guo Songzhi and annotated by Wang Zhu, Song Qi, Wang Anshi, Huang Tingjian, Xue Mengfu, Du Tian, Bao Biao, Zhao;
A detailed explanation of Du Fu's poems in Qing Dynasty.
Modern:
Selected Works of Du Fu annotated by Deng Kuiying and Nie Shiqiao, Shanghai Ancient Books Edition;
Notes on Du Fu's Selected Poems and Notes on Xiao Difei, People's Literature Edition;
Selected Poems of Du Fu, annotated by Zhang Zhonggang, Zhonghua Book Company.
See also:
Feng Zhi's Biography of Du Fu.
By Li Bai, Du Fu and Guo Moruo