Thornadtsson A., Drca N., Ricciardolo F., and Högman M. “Increased Levels of Alveolar and Airway Exhaled Nitric Oxide in Runners”. Upsala Journal of Medical Sciences, vol. 122, no. 2, May 2017, pp. 85–91, doi:10.1080/03009734.2017.1317886.