We read and cited in our manuscript the suggested and other references that correspond to [25], [31], [32], [33], [34], [35] and [36] (especially in Section 2.2) in revising our conceptual framework.
There are also existing reviews of cluster policies in Europe that should be considered (Clusters are Individuals, 2012, BMWi; VDI/VDE; Dasti). There is also a growing literature on cluster initiative management in Europe (see the EU's "Excellence Initiative' with the benchmarking of cluster initiatives) that should be considered.