Characteristics of subjects unable to perform even a single acceptable spirometry maneuver (ATS grade F) identified within a cohort of 10,193 subjects - Ram, Babu; Muthu, Valliappan; Sehgal, Inderpaul S.; Dhooria, Sahajal; Agarwal, Ritesh; Aggarwal, Ashutosh N.; Prasad, Kuruswamy T. (Lung India, 2023)