法国预测与国际信息中心：知识在空间中的渗透（英文版）

This paper shows that the negative effect of geographical distance on knowledge flows stems from how firms gain sources of knowledge through their existing network. We start by documenting two stylized facts. First, in aggregate, the distance elasticity of patent citations flows has remained constant since the 1980s, despite the rise of the internet. Second, at the micro level, firms disproportionately cite existing knowledge sources, and patents cited by their sources. We introduce a framewo