Online references to public sites where papers on decision tree learning, machine learning and data mining can be obtained are listed below. Direct links to some of the papers mentioned in the tutorial section of this site are provided at the bottom of the corresponding pages. Academic research papers are not always publicly available though and are only available via subscriptions (such as for the IEEE journals and Kluwer's Machine Learning).

Citeseer

http://citeseer.nj.nec.com/cs

One of the largest collections of links to online publicly available research papers and articles. Full text downloads in PDF or PS. A lot of recent papers can be found here on topics such as hybrid decision trees and combining mutliple models. A good place to start.

Ross Quinlan's Homepage

http://www.rulequest.com/Personal/

Many useful and relevant papers on decision tree learning can be found here.

There are also some links directly to papers in the tutorial section.

Collection of Tutorials and videos on Data mining and Decision Trees.
Tutorials: http://www.dataminingtools.net/browsetutorials.php
Videos: http://www.dataminingtools.net/browse.php