“…Firms can identify or search for external sources of innovation by collaborating with a variety of external stakeholders or seeking out specialists with useful knowledge (e.g., Ili, Albers, and Miller, ; Nieto and Santamaría, ; Tether and Tajar, ); firms may also passively obtain innovation that is “pushed” by external stakeholders (Spaeth, Stuermer, and von Krogh, ). Researchers have identified specific sources of external knowledge including suppliers (Li and Vanhaverbeke, ; Schiele, ), customers (Gassmann, Sandmeier, and Wecht, ; Grimpe and Sofka, ), competitors (Lim, Chesbrough, and Ruan, ), or universities (Cassiman, Di Guardo, and Valentini, ; Fabrizio, ; Harryson, Kliknaite, and Dudkowski, ). Factors that influence the use of external sources of innovation include not only the characteristics of the external source, but also internal factors such as R&D capabilities and complementary assets (Ceccagnoli, Graham, Higgins, and Lee, ; Teirlinck, Dumont, and Spithoven, ).…”