IMPACT ON FIRMS OF THE USE OF KNOWLEDGE EXTERNAL SOURCES: A SYSTEMATIC REVIEW OF THE LITERATURE
系统综述了关于企业使用外部知识来源（大学、研究机构、知识密集型商业服务）影响的实证文献，总结了哪些企业使用、效果如何以及谁受益最多，并提出未来研究方向。
Abstract This study summarizes the main conclusions from a systematic review of the empirical literature regarding the impact on firms of the use of knowledge external sources (universities, research institutes and knowledge intensive business services). With the aim to organize the literature, we classify the different works according to the research question addressed: (i) which firms use knowledge external sources?; (ii) Do firms using knowledge external sources achieve better results?; And (iii) which firms benefit the most from using knowledge external sources? Stylized facts are that larger, more R&D intensive and high tech firms are more likely to use knowledge external sources and that use of knowledge external sources is associated to firms higher technical results. Less attention has been paid to the third question and evidence is not conclusive. Several recommendations for future research emerge. First, to take in greater consideration methodological issues so that potential biases in the results caused by sample selection and endogeneity are handled properly. Second, to pay more attention to heterogeneous outcomes. Third, to use continuous indicators of depth and breadth of links allowing for non‐linear relationships and fourth, to extend evidence for developing countries and service industries.