* {{cite book | last=Harman | first=P. M. | title=The Natural Philosophy of James Clerk Maxwell | publisher=Cambridge University Press | publication-place=Cambridge, UK ; New York | date=2001-02-22 | isbn=0-521-00585-X}}
<ref name="s740">{{cite book | last=Harman | first=P. M. | title=The Natural Philosophy of James Clerk Maxwell | publisher=Cambridge University Press | publication-place=Cambridge, UK ; New York | date=2001-02-22 | isbn=0-521-00585-X | page=}}</ref>