Bloem, Ada, Marcel Veltkamp, Martijn A. Spruit, Jan W.H. Custers, Eric W.P. Bakker, Hanneke M. Dolk, and Jan C. Grutters. “Validation of 4-Meter-Gait-Speed Test and 5-Repetitions-Sit-to-Stand Test in Patients With Pulmonary Fibrosis: A Clinimetric Validation Study”. Sarcoidosis vasculitis and diffuse lung disease 35, no. 4 (November 28, 2018): 317-326. Accessed October 20, 2019. http://mattioli1885journals.com/index.php/sarcoidosis/article/view/7035.