* {{cite book | last=Wilson | first=Kenneth George | title=The Columbia Guide to Standard American English | publisher=Columbia University Press | publication-place=New York | date=1993 | isbn=0-231-06989-8}}
<ref name="z024">{{cite book | last=Wilson | first=Kenneth George | title=The Columbia Guide to Standard American English | publisher=Columbia University Press | publication-place=New York | date=1993 | isbn=0-231-06989-8 | page=}}</ref>