Xian, Xiaowei; Zhang, Linyuan; Ai, Nanshan; Wihelm, Wohlke (March 1, 1991). „On the relation between the evolution of natural environment and human factors and the development of urban settlement—Take the Lanzhou Valley Basin as an examples“. Chinese Geographical Science. 1 (1): 42–53. doi:10.1007/BF02664455. S2CID195214733.
Xian, Xiaowei; Zhang, Linyuan; Ai, Nanshan; Wihelm, Wohlke (March 1, 1991). „On the relation between the evolution of natural environment and human factors and the development of urban settlement—Take the Lanzhou Valley Basin as an examples“. Chinese Geographical Science. 1 (1): 42–53. doi:10.1007/BF02664455. S2CID195214733.
