Usability in Logos
http://www.senseandusability.com/index.php?view=article&catid=35%3Ausability&id=56%3Ausability-in-logos&option=com_content&Itemid=58

Lanier, Clinton R.
sense and usability
2007

Abstract:

Principles of usability can apply to everything, not just physical objects. When using or creating graphics, documents, symbols or logos, stop and try to think about whether or not the item is usable.