<?xml version="1.0"?>
<dblp>
<article key="journals/tcs/Ibarra05" mdate="2005-05-06">
<author>Oscar H. Ibarra</author>
<title>On membrane hierarchy in P systems.</title>
<pages>115-129</pages>
<year>2005</year>
<volume>334</volume>
<journal>Theor. Comput. Sci.</journal>
<number>1-3</number>
<ee>http://dx.doi.org/10.1016/j.tcs.2004.05.007</ee>
<url>db/journals/tcs/tcs334.html#Ibarra05</url>
</article>
</dblp>
