* {{cite book | last=Nicholls | first=David | title=The Cambridge Companion to John Cage | publisher=Cambridge University Press | publication-place=Cambridge ; New York | date=2002-08 | isbn=0-521-78968-0}}
<ref name="n660">{{cite book | last=Nicholls | first=David | title=The Cambridge Companion to John Cage | publisher=Cambridge University Press | publication-place=Cambridge ; New York | date=2002-08 | isbn=0-521-78968-0 | page=}}</ref>