Valk G D, de Sonnaville J J, van Houtum W H, Heine R J, van Eijk J T, Bouter L M, Bertelsmann F W
Department of Neurology, Institute for Research in Extramural Medicine, Free University Hospital, Amsterdam, The Netherlands.
Muscle Nerve. 1997 Jan;20(1):116-8. doi: 10.1002/(sici)1097-4598(199701)20:1<116::aid-mus19>3.0.co;2-2.