1. Brown RH Jr Amyo tropic lateral Sclerosis and other Motor Neuron Disease chapter 374pp 3345 in HPIM-18 edition.
2. Low PA Emgstrom JW: Disorder of the Nervous system chap375 pp3351 in HPIM-18
3. Hirano I, KahirilasPJ: Dysphagia chap 38 pp297
4. KahirilasPJ, Hirano I Disease of oesophagus.
5. Constipation: Camilleri M Murray JA: Diarrhoea and constipation chap40pp308.