David G. Simons, Siegfried Mense: Understanding and measurement of muscle tone as related to clinical muscle pain. In: Pain. Band75, Nr.1, 1998, S.1–17, doi:10.1016/S0304-3959(97)00102-4 (englisch).
nih.gov
ncbi.nlm.nih.gov
Taeko Sakuma-Sasai, Yuichi Inoue: (Rapid eye movement (REM) sleep behavior disorder in older adults). In: Nihon rinsho. Japanese journal of clinical medicine. Band71, Nr.10, Oktober 2013, S.1853–1857, PMID 24261219 (japanisch).