Morton, A. P., Fitch, K. D., & Hahn, A. G. (1981). Physical activity and the asthmatic. The physician and sportsmedicine, 9(3), S. 51-64.

Morton, Alan P., Kenneth D. Fitch, and Allan G. Hahn. "Physical Activity and the Asthmatic." The Physician and Sportsmedicine 9, no. 3 (1981): S. 51-64.

Morton, Alan P., Kenneth D. Fitch, and Allan G. Hahn. "Physical Activity and the Asthmatic." The Physician and Sportsmedicine 9.3 (1981): S. 51-64.