Source:http://linkedlifedata.com/resource/umls/id/C1158021
GO: The chemical reactions and pathways resulting in the breakdown of any one of a family of organic molecules consisting of a purine or pyrimidine base covalently bonded to a sugar ribose (a ribonucleoside) or deoxyribose (a deoxyribonucleoside). [GOC:jl]