International Journal of Geo-Information Article Geographic Knowledge Graph (GeoKG): A Formalized Geographic Knowledge Representation Shu Wang 1,2,3 , Xueying Zhang 1,2,3,*, Peng Ye 1,2,3 , Mi Du 1,2,3, Yanxu Lu 1,2,3 and Haonan Xue 1,2,3 1 Key Laboratory of Virtual Geographic ...