Janson Christer, Gislason Thorarinn, Laxmyr Lena, Boman Gunnar, and Persson Carl. 1991. “Sleep Disturbances in Asthma: Theophylline Versus Enprofylline”. Upsala Journal of Medical Sciences 96 (2):119-27. https://doi.org/10.3109/03009739109179265.