COMASCO E., NORDQUIST N., GÖKTÜRK C., ÅSLUND C., HALLMAN J., ORELAND L., and NILSSON K. W. “The Clock Gene PER2 and Sleep Problems: Association With Alcohol Consumption Among Swedish Adolescents”. Upsala Journal of Medical Sciences, vol. 115, no. 1, Mar. 2010, pp. 41–48, doi:10.3109/03009731003597127.