Nasal NO measurement by direct sampling from the nose during breathhold: Aspiration flow, nasal resistance and reproducibility. - Struben VM; Wieringa MH; Mantingh CJ; de Jongste JC; Feenstra L (European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery, 2006)