Albiach-Serrano, A., Bugnyar, T., & Call, J. (2012). Apes (Gorilla gorilla, Pan paniscus, P. troglodytes, Pongo abelii) versus corvids (Corvus corax, C. corone) in a support task: The effect of pattern and functionality. Journal of Comparative Psychology, 126(4), 355-367. doi:10.1037/a0028050.