The book Usability Inspection Methods, edited by Jakob Nielsen and Robert L. Mack, is the first comprehensive, book-length work in the field of usability evaluation and includes a full complement of UI strategies, tools, and techniques.| Nielsen Norman Group
Jakob Nielsen's textbook on applying systematic methods throughout the development lifecycle to increase ease-of-use for software, websites, and other user interfaces. Emphasis on cheap and fast methods.| Nielsen Norman Group
Elaborate usability tests are a waste of resources. The best results come from testing no more than 5 users and running as many small tests as you can afford.| Nielsen Norman Group