Wheatcroft, D., Price, T., & Wheatcroft, D. (2013). Learning and signal copying facilitate communication among bird species. Proceedings. Biological Sciences, 280(1757), 20123070–20123070. doi10.1098/rspb.2012.3070
Witzany, Günther. (2006). Plant communication from biosemiotic perspective: Differences in abiotic and biotic signal perception determine content arrangement of response behavior. context determines meaning of meta-, inter- and intraorganismic plant signaling. Plant Signaling and Behavior, 1(4), 169–178. https://doi.org/10.4161/psb.1.4.3163