Gregory, A. M., Rijsdijk, F. V., Lau, J. Y. F., Dahl, R. E., & Eley, T. C. (2009). The Direction of Longitudinal Associations Between Sleep Problems and Depression Symptoms: A Study of Twins Aged 8 and 10 Years. Associated Professional Sleep Societies, LLC.

Gregory, Alice M., Früuhling V. Rijsdijk, Jennifer Y. F. Lau, Ronald E. Dahl, and Thalia C. Eley. The Direction of Longitudinal Associations Between Sleep Problems and Depression Symptoms: A Study of Twins Aged 8 and 10 Years. Associated Professional Sleep Societies, LLC, 2009.

Gregory, Alice M., et al. The Direction of Longitudinal Associations Between Sleep Problems and Depression Symptoms: A Study of Twins Aged 8 and 10 Years. Associated Professional Sleep Societies, LLC, 2009.