<?xml version="1.0"?>
<dblp>
<article key="journals/jsyml/Langford39" mdate="2003-11-20">
<author>C. H. Langford</author>
<title>A Theorem on Deducibility for Second-Order Functions.</title>
<pages>77-79</pages>
<year>1939</year>
<volume>4</volume>
<journal>J. Symb. Log.</journal>
<number>2</number>
<url>db/journals/jsyml/jsyml4.html#Langford39</url>
</article>
</dblp>
