Integrating Usability and Accessibility
http://www-3.ibm.com/ibm/easy/eou_ext.nsf/Publish/50?OpenDocument&../Publish/1114/$File/paper1114.pdf

Johannesen, Leila, Joe Sacco, Tim Hogan and Marc Boegner
IBM
2004

Abstract:

Usability is a concept that we intuitively know when we experience it. The notion of usability can refer to ease of use, ease of learning, efficiency and usefulness. To render a satisfying user experience, a well-designed product should have a combination of these features.