Lekkeikerker, C., and J. Boland. 1962. “Representation of a Finite Graph by a Set of Intervals on the Real Line.” Fundamenta Mathematicae 1(51): 45–64.
<a href="//commons.wikimedia.org/wiki/User_talk:0g1o2i3k4e5n6" title="User talk:0g1o2i3k4e5n6">0g1o2i3k4e5n6</a>
<span class="int-own-work" lang="en">Own work</span>