The set of publication Paul produced is impressive - you probably don't have time to read all of them ;-) but at least take a look at the following ones: an extension to KLM for mobile phones , an integrated development environment that includes usability models , and a explorative study in wearable computing .
In Germany we have a tradition to make a hat for the candidate. Paul's hat has items on it that insiders can interpret, including a world map with bikes, miniature TEI'07 proceedings, Birkenstock shoes, a key with a label "Amsterdam", a display, a phone, a yoyo, a control unit for vibration motors, 4 flags of town, and some context-aware plug-and-play hardware (and obviously batteries).
 Holleis, P., Otto, F., Hussmann, H., and Schmidt, A. 2007. Keystroke-level model for advanced mobile phone interaction. InProceedings of the SIGCHI Conference on Human Factors in Computing Systems (San Jose, California, USA, April 28 - May 03, 2007). CHI '07. ACM, New York, NY, 1505-1514. DOI=http://doi.acm.org/10.1145/1240624.1240851
 P. Holleis, A. Schmidt: MakeIt: Integrate User Interaction Times in the Design Process of Mobile Applications. 6th International Conference on Pervasive Computing (Pervasive'08), Sydney, Australia, May 2008
 Holleis, P., Schmidt, A., Paasovaara, S., Puikkonen, A., and Häkkilä, J. 2008. Evaluating capacitive touch input on clothes. InProceedings of the 10th international Conference on Human Computer interaction with Mobile Devices and Services(Amsterdam, The Netherlands, September 02 - 05, 2008). MobileHCI '08. ACM, New York, NY, 81-90. DOI= http://doi.acm.org/10.1145/1409240.1409250