Nighttime light imagery or mobile phone footprints: Which better reflects urban socio-economics at the grid level? A case study in the Pearl River Delta, China. - Jinzhou Cao; Xianyu Cao; Wei Tu 001; Xiaoliang Tan; Tong Wang 017; Guanzhou Chen 001; Xiaodong Zhang 027; Qingquan Li (Comput. Environ. Urban Syst., 2025)