Gregory, A. M., Rijsdijk, F. V., Lau, J. Y., Dahl, R. E., & Eley, T. C. (2008). The direction of longitudinal associations between sleep problems and depression symptoms: a study of twins aged 8 and 10 years. 17, 140–141.

Gregory, A. M., et al. The Direction of Longitudinal Associations between Sleep Problems and Depression Symptoms: a Study of Twins Aged 8 and 10 Years. 2008, pp. 140–41.

Gregory, AM, FV Rijsdijk, JY Lau, RE Dahl, and TC Eley. 2008. “The Direction of Longitudinal Associations between Sleep Problems and Depression Symptoms: a Study of Twins Aged 8 and 10 Years.” In , 17:140–41.