Ackermann, C. Y., Neumann, C., Crockford, C., Deschner, T., Wittig, R. M., & Zuberbuehler, K. (2017). Variation in strength of juvenile-mother bonds and oxytocin in wild juvenile chimpanzees. Folia primatologica, 88(2), 176. doi:10.1159/000479094.