<?xml version="1.0"?>
<dblp>
<article key="journals/tods/Biskup83" mdate="2006-04-03">
<author>Joachim Biskup</author>
<title>A Foundation of Codd's Relational Maybe-Operations.</title>
<pages>608-636</pages>
<cdrom>TODS8/P608.PDF</cdrom>
<year>1983</year>
<volume>8</volume>
<journal>ACM Trans. Database Syst.</journal>
<number>4</number>
<url>db/journals/tods/tods8.html#Biskup83</url>
<ee>http://doi.acm.org/10.1145/319996.320014</ee>
<ee>db/journals/tods/Biskup83.html</ee>
<cite>...</cite>
<cite>conf/vldb/BeeriBG78</cite>
<cite>conf/adbt/Biskup79</cite>
<cite>...</cite>
<cite>...</cite>
<cite>journals/tods/Codd79</cite>
<cite>journals/cacm/Codd82</cite>
<cite>conf/adbt/77</cite>
<cite>journals/ipl/Grant77</cite>
<cite>journals/ipl/Grant79</cite>

<cite>...</cite>
<cite>conf/vldb/ImielinskiL81</cite>
<cite>...</cite>
<cite>journals/tods/Lipski79</cite>
<cite>journals/jacm/Lipski81</cite>
<cite>conf/adbt/NicolasM77</cite>
<cite>conf/adbt/Reiter77</cite>
<cite>books/cs/Ullman80</cite>
<cite>conf/sigmod/Vassiliou79</cite>
<cite>conf/vldb/Vassiliou80</cite>

<cite>...</cite>
</article>
</dblp>
