Here are the details of the books quoted in the cost benefits of usability section.

Boehm, B.W., 1981,               Software Engineering Economics, Prentice-Hall, Englewood Cliffs NJ.

Alan Cooper, 2004,                The inmates are running the asylum,  Sams Publishing, Indianna

Karat, C. 1993,                       Cost benefit and business case analysis of usability engineering, 
                                              Bridges between worlds, INTERCHI’93, Tut. Notes 23,
                                              AdisonWesley, Reading

Lederer, A & Prasad, J, 1992,  Nine Management Guidelines for Better Cost Estimating,             
                                              Communications of the ACM, Vol 35, No 2, 51 -59

Neilsen, J, 1993,                      Usability Engineering, AP Professional, Cambridge MA