Portable Devices Can Cause Usability Problems
http://webword.com/moving/portable.html

Rhodes, John S.
WebWord
1999

Abstract:

Take a moment and think about the various portable Internet devices available. You see everything from wireless hand held devices, to web-enabled pagers, to cellular phones with email access. The list goes on and on. Every day you can scan the technology headlines and read about several new Internet technologies being announced. Think about the nature of these portable Internet devices: they probably are not very usable.