<?xml version="1.0"?>
<dblp>
<article key="journals/mlq/Apter07" mdate="2007-12-03">
<author>Arthur W. Apter</author>
<title>Indestructibility and level by level equivalence and inequivalence.</title>
<pages>78-85</pages>
<year>2007</year>
<volume>53</volume>
<journal>Math. Log. Q.</journal>
<number>1</number>
<ee>http://dx.doi.org/10.1002/malq.200610028</ee>
<url>db/journals/mlq/mlq53.html#Apter07</url>
</article>
</dblp>
