Shoji, Hirotaka, Nakane, Ayako, Mikushi, Shinya, Yoshida, Sachiko, Yoshino, Hide, Numasawa, Yoshiyuki, Ishihara, Shouichirou, AND Minakuchi, Shunsuke. " The variety of dysphagia progression in amyotrophic lateral sclerosis (ALS)" Medical Research Archives [Online], Number 3 (11 June 2015)