Management of respiration in MND/ALS patients: an evidence based review. - Heffernan, C; Jenkinson, C; Holmes, T; Macleod, H; Kinnear, W; Oliver, D; Leigh, N; Ampong, M (Amyotrophic lateral sclerosis : official publication of the World Federation of Neurology Research Group on Motor Neuron Diseases, 2006)