Carter, N.T., Dalal, D.K., Boyce, A.S., O'Connell, M.S., Kung, M-C., & Delgado, K.M. (2013). Uncovering curvilinear relationships between conscientiousness and job performance:

Le, H., Oh, I-S., Robbins, S.B., Ilies, R., Holland, E., & Westrick, P. (2011). Too much of a good thing: Curvilinear relationships