⁴The database for the Aviation Valley study in Poland has been collected in the framework of a research project Effective Clusters – Basis for Innovation and Source of Sustainable Regional Development. The authors wish to thank Krzysztof Kaszuba for his advice on the sources of secondary data, Emilia Barbara Sieńko-Kułakowska and Grzegorz Pisarczyk for their great assistance in collecting primary data, and Waldemar Ratajczak for advice on the various research steps. The detailed source data are contained in the relevant background documents for this project.